If it was such a great design for ground attack, why has no other country followed up with a minimum wing area aircraft for the air to mud role?
Because it was NOT a "mud mover". It was a high speed, low level, penetration delivery system for tactical nuclear weapons.
There is a world of difference between the roles. "Mud movers" are not moving at trans-sonic speeds in full ground effect environments.
F-105 was $2.14M in 1960, the F-104 was $1.5M, had 360mile less range, worse avionics, and 10,000 pound less ordnance.
Canadair delivered CF-104G's to the RCAF for $1M (CDN). Republic struggled with the F-105 project. Look into the "Cooke-Craige" production system utilized during the period and it's effects on subsequent rework required after delivery, to bring about standardized maintenance schedules. Load out and tonnage is irrelevant. The CF-104 carried one B28/B61 weapon on the centerline station. Disposable fuel cans on the underwing points and on the wingtips. Mission profile in a hot war is to get rid of the underwing tanks prior to crossing the inter-German border, get down as low as practical on the pre-planned flight path and cross the border in AB @ Mach whatever the thing will give you. Fly your route until the computer tells you it's time to "go north". Let it take care of releasing the bomb (another 30nm+/- down range), while you are squashed in your seat undergoing 7-9G (tip tanks are gone by this point). RTB for more tanks, a new route, and another weapon...if there's actually a "B" to "RT" to...
Also? With regards to avionics? All CF-104G's were equipped with Autonetics NASARR, but they actually had the more advanced F-15 version, superior (for toss bombing) to the R-14 unit fitted to the F-105.
F-105 had 14.7 accidents per 100,000 flying hours, F-104 in US service was 26.7
The USAF only operated the A & C versions of Kelly's rocket. My guess (your source would be really handy here...just saying) is that the MAP 104's at Luke AFB probably get lumped into your ratio (as they had USAF "tails" assigned to them???).
The modifications made to the G (increased rudder/vertical stabilizer area) were significant. It still didn't prevent people auguring into German hillsides while doing 700+TAS <500AGL (or sucking up birds, or suffering bleed air issues/compressor stalls/pitch-up "events"). This was the job description; there was no shortage of guys that wanted to strap that thing on and go for a ride.
Accident rates were viewed as a cost of doing business (cold, but true) in the period...look to the F-86 and F-100 numbers per 100K/hrs.
It was a different time.