They arent. Nobody was buying them.
No. EPA and safety rules mandated them out of existence.
Nice conspiracy theory, but no. Among other problems, the market demanded larger vehicles and the value proposition wasnt there. The compact pickups cost 3/4-7/8 what a stripped down full size truck did and they werent 3/4-7/8s as much truck.
In fact, CAFE and other regs made it so companies would *greatly* benefit if makers made smaller trucks as this would boost their truck CAFE numbers. This is why GM kept the Tracker in their lineup so long, to cite one example. However, people stopped buying them in the 2000s so the trucks either had to upsize or go away.
The two door SUV has basically gone away for the similar reasons. There are only two left on the US market - the Jeep Wrangler and a really expensive Land Rover thats about to get canceled. And Chryslers said that since more than 75% of Wrangler sales are of the four door version, if demand drops much more for the two door, it will be canceled.