If they have a car that drives around and looks cool, they can and may sell it.
The ones that get wrecked can not be retitled as useable. You may be able to buy it and display it wrecked or even fixed. Some companies may still, like smaller production companies. But large ones write it off as a production expense and move on.
Once they wreck it it becomes a liability.
If they sell it to you and something breaks causing a wreck they can be sued, even if it was fine and the wreck had nothing to do with their damages. So they scrap most all of it. That way there's no liability.
Unfortunately a lot of shows where carcraft or hotrod, etc. built a car they were ultimately destroyed also. For the same reason. They modified it, and lawyers can run with that.
That's actually one of the reasons Stacey David started his own show. He didn't like seeing stuff he built get destroyed. So he did his own show where he can fund his own trucks and decide for himself what happens.
