I'm sorry to disagree, but air forces killed very large numbers of Chinese, and North Korean troops. The NKPA had many truck convoys blasted off the roads. Air support had a decisive effect at the Pusan Perimeter. The U.S. 2nd ID would have been destroyed during its retreat though the gauntlet, if not for the air support they received. The 1'st Marine Division, and the rest of X Corps wouldn't have survived without the heavy air support they had. The communist forces were largely limited to night movement because of UN Air Power. Every account of the war, on both sides testifies to the devastating effects of air attacks, practically regarding napalm.
Oh sure, air power
claimed to do plenty of damage, but there's no evidence those claims have any attachment to reality. Certainly, continuous, unchallenged tactical air support can have a great suppressive effect on ground formations out of all proportions to the physical damage inflicted, which can often be of great aid to ground forces, but that's still more a psychological effect then a physical one. Chinese and North Korean records either don't break down cause of losses to that degree or are unavailable (respectively), but looking at the actual historical effect of air power on ground-based targets in other conflicts where such studies are eventually done that do break down losses tells us the damage inflicted must have been vastly more limited than claimed.
At the Pusan Perimeter, the decisive effect was American numerical superiority, not air power. By then the US outnumbered the North Koreans by 1.44:1 in manpower and 10:1 in operational armor (500 AFVs vs just 50). North Korean logistics during its lunge south were borked from the beginning (they had attempted to imitate the Soviet logistical model despite lacking both the organization and material overhead to do that), exacerbating the numerical difference. And of course the Americans had vast firepower superiority in artillery, the main killer throughout the war.
What we do know is that in 1950-51, Communist logistical difficulties stem more from material-organizational factors then the presence of American airpower, with the North Koreans and Chinese simply having too few assets, especially long-distance transports like trucks and trains, and these were poorly organized. The 2nd Infantry's division escape from the pocket was mainly attributed to it expending all of its artillery munitions on it's own part and the failure of the Chinese to concentrate the pocket defenses along the road (they attempted to maintain a 360 perimeter, resulting in lines that were spread just a bit too thin) and even then it
was effectively destroyed by the military definition of the term.
Air power is more attributable to the survival of the 1st Marine Division, with a critical air dropped pontoon bridge being allowing the Marines to replace a critical bridge vital to escape, but even there the Chinese repeated the aforementioned mistake "360 defense mistake, didn't concentrate along the roads" (something the Marines themselves acknowledged) and we know that all US claims from that battle about the casualties they inflicted on the Chinese are hideously exaggerated: the figures presented there (25,000 killed and 12,000 wounded, mostly by airpower) are flat out impossible for a number of reasons: airpower has
never done so well against light infantry in rough mountainous terrain, particularly given the care the Chinese took to hide from air attack. Airpower also has
never inflicted so grossly disproportionate a killed to wounded figure. And above all because the figure would have meant most of the Chinese troops chasing the Marines were wiped out, which could not have happened since all but one of the pursuing divisions were involved in the later fighting around Seoul (where they again successfully threw back the Americans) almost immediately.
Basically, during the Korean War Marine and Air Force pilots just "estimated" how much they killed and how much damage they inflicted, which is to say they really had no idea how many they killed and how much damage they were doing. The same thing happened earlier in WW2 and later in Vietnam.
