Deliverance,
I would hazard a guess that the millions southside is talking about start with the additional wear and tear hence reduced airframe life and greater maintenance and replacement costs.
Then you get the cost arising from low level accidents, thankfully fewer and less life threatening than in the 60s and 70s. During the cold war with virtually no combat flying all the costs fell during training and none during operations - except in Vietnam.
That is where the US switched their game. They were taking SAC pilots, converting them to FJ and sending them to war. Although they had flown at LL there was no way you would have considered them LL Operational to the same extent as a modern mud sqn training for war. I am not denigrating the SAC pilots, simply suggesting that the USAF increased the size of their aircrew pool to such an extent that giving them all low level training was too expensive when the better option was a SEAD package.