"They certainly couldn't raise pay much to attract candidates due the smaller amount of revenue the smaller aircraft generate"

Yeah they could. Amflight does UPS contracts. UPS HAS to move those boxes. Amflight could raise what they charge UPS and UPS would pay it. As long as the bar gets lifted equally across the board, the large 135 operators could pay much better and pass it on to the customer. Some of the little outfits might not survive.