As others have noted that's not at all true as it was the Army/Marine, (mind you including out ALLIES Army command btw) pressure for the Air Force to field a "REAL" CAS aircraft that got the A-10 deisigned and into production. The Air Force itself never wanted or liked the A-10 and tried everything it could to get either an F-16, (though to be fair most of the AF command never liked the 'light-weight-fighter' concept either) or F-15 version as a CAS aircraft. They managed to finagle the Strike Eagle which was supposed to replace the A-10 but it was a two man aircraft among other 'issues' that ended up reducing its utility as a "fighter" aircraft.
(Mind you, one F-15E has the unique distinction of having taken out an Iraqui HInd Attack Helicopter in an "air-to-air" fight by hitting it with a paveway guided bomb so ...
)
The AC-130 was another aircraft the Air Forced initially didn't want but the need was pretty clear as you needed a long-loiter, slow speed but high capacity platform that could 'orbit' an area and put accurate firepower on the bad guys and not the good guys. The original "Puff's" did just that, in large volume so it was clear that "zoom-and-boom" wasn't the best option for CAS. Hence WHY you got the development of the A-10. (And the Frogfoot once the USSR got the idea)
The problem with something like the AC-130 is that in order to get that accuracy it has to fly slow and pretty 'low' which makes it vulnerable to ground fire. The A-10 can get in and out faster at a lower altitude with pretty much the same accuracy even without guided weapons.
Being ex-AMMO yes those vids ARE great viewing no matter the delivey system
Actually if we're being honest here "popular myth" on the A-10 is exactly the opposite as we've already seen in that it is suggested it is FAR from the 'best plane' for the job and that it can't survive on the modern battlefield, is too slow, too easy to damage and obsolete. The actual evidence would appear to show the opposite
Lets re-phrase that a bit and see if it makes any more sense: How much is the real or imagined effectivness of the Cobra Attack Helicopter due to its single mission role and the crews doing nothing else but train for CAS? Continue that through the rest of the questions and then ask yourself why the Army trains pilots in the CAS mission when those pilots could be utliized in possibly more effective ways if they could also do OTHER air missions such as supply delivery and ar-superiority. Then ask yourself the BIG question: Why is a service who's MAIN goals are air-defense/offense/interdiction, strategic and tactical, (but NOT actual 'close air support) bombing and air logistics transport tasked with Close Air Support of VERY front-lines units? The Marine Corps has a seperate air service that is trained mostly in CAS but also has air-to-air and tactical bombing capability and training... Why doesn't the US Army? The 'answer' is the US Air Force and its post WWII attempts to grab control of all US military "flight" under it's banner
The on-going 'battle' over the A-10 is in fact a continuation of that conflict since it is an aircraft the Air Force never wanted and has been trying to get rid of for decades BECAUSE it has one and only one task of supporting the ground forces in close contact with enemy forces. The problem is that is exactly what those front-line ground forces NEED rather than a multi-role aircraft that can 'toss' some 'smart' bombs at the situation and hope things work out while it flies past at 300mph. This isn't a new or unique issue since it's been ongoing since the middle of WWI and I doubt it will ever go away unless someone gets smart and gives the Army back its own aircraft based CAS. (Fun fact, that was actually scheduled to happen! In 1990 the Air Force and Army cooperated to convince Congress to allow the Air Force to transfer their A-10s to the Army with the AF providing training (or transfering) pilots for the Army till they could stand up their own training and recruitment program. The AF insisted the Army call them OV-10s rather than "A"-10s because there was an informal agreement that the Army couldn't have fixed wing "attack" aircraft but could have fixed wing "observer" (OV) aircraft. The Army agreed and began drawing down it's force of OV-10 Bronco prop aircraft but...
There arose a little 'tif' in the middle-East that suddenly showed how great the A-10 actually worked and the Air Force had to decline the original deal and keep the A-10s. (And then start multiple program to 'replace' it with some variation of the F-16/15 and/or next generation "multi-role" fighter
)
When the GAU-8 was designed (early 70s) the DPU, (Depleted Uranium Armor Penetrator) round was supposed to be able to if not penetrate at least significantly damage the then standard Soviet armor. The GAU however wasn't actually tasked with ripping up tanks but APC's and other 'lightly' or unarmoured targets while the Mavrick's bombs and rockets were saved for the actual armored targets. Meanwhile even if the DPU rounds didn't penetrate the tank armor it would have a side effect of making it more difficult for infantry to move in close support of, or ride the armor due to the residual radioactivity. (Don't laugh, it was a 'plausible' concern since we were actually copying the concept from several "new" models of Soviet A2A missiles that they were deploying which had radioactive isotopes incorperated into the warheads for a similar purpose. Note that it SHOULD have been clear that this wasn't going to be a very effective tactic but they both went with it anyway
)
In fact the DPU round doesn't actually have to penetrate the armor to do damage as the knetic transfer of multiple impacts DID cause the plate to flex and this could generate a 'spall' off the interior armor which would bounce around and damage the interior or crew. This was a known effect of these type of rounds and had a pretty easy 'fix' (flex layer which ironically in US tanks is a layer of depleted uranium
) but is something you can't actually 'retrofit' but have to re-armor the tank which gets expensive.
They went with a 30mm round due to the needed propulsion charge needed for the DPU round and this drove the rest of the gun requirements along with the eventual design of the A-10. The problems with the GAU-8 is why we designed a high velocity, long range 25mm gatling gun for an A-10 "replacement" CAS aircraft which was eventually fitted onto the AC-130 to replace the shorter range 20mm gatling guns. The 'plan' (if they ever actually get around to it at any rate) is to mount a similar gun on the next-gen CAS dedicated aircraft which the Air Force isn't wanting but the ground-pounders do. The 'problem' is it's become less and less reasonable to be able to mount a plausible "armore killing" gun on an aircraft smaller than a transport...
Not to say we haven't tried though
One of the main worries about the A-10 in the Fulda Gap was the often stated fact that the Soviet's had more tanks than we had missiles to kill them with. So one idea was to mount an out-and-out cannon, (75mm/105mm+ caliber) on a 'fighter' and have it pound the tanks alongside the A-10.
(Ignore the circular and often silly back-and forth arguments and check out the links here:
https://www.secretprojects.co.uk/threads/the-future-of-aircraft-mounted-guns.31221/, no I'm NOT the OP but I do try and contibute to the subject
)
While it seems crazy keep in mind we already do this with the AC-130 and have tested it on things like the OV-10A (auto-loading 90mm recoiless rifle) and there are patents to 'modernize' the idea by putting them on the B-1B. (
https://pdfpiw.uspto.gov/.piw?PageNum=0&docid=09963231&IDKey=666A1766EFB3 &HomeUrl=http://patft.uspto.gov/netacgi/nph-Parser?Sect1=PTO2%26Sect2=HITOFF%26p=1%26u=%252Fnetahtml%252FPTO%252Fsearch-bool.html%26r=1%26f=G%26l=50%26co1=AND%26d=PTXT%26s1=%25229,963,231%2Bb2%2522%26OS=%26RS=,
https://www.military.com/defensetech/2018/05/17/proposed-cannon-would-turn-b-1-bomber-gunship.html)
Add in guidance and propulsion assist, (rocket/ramjet/etc) it's got some force multiplier possiblites when augmented with mini-missiles and drones.
Randy