It's slightly different than that. The light truck sales essentially pay for all of the other regulations the politicians want. They regulate all other vehicles

It's slightly different than that. The light truck sales essentially pay for all of the other regulations the politicians want. They regulate all other vehicles into unprofitability, but avoid destroying the manufacturers by allowing them to make all their money on huge "light" trucks. If they didn't have this exception, they wouldn't be able to enact all the other regulations without killing the auto industry.