I had a great time recently on my first trip to a racetrack, and the most surprising thing to me was how all the cars were utterly beat to shit. Not like in a bad way, but in like... a sports gear way? They were all working (well, mostly, one guy had a real bad time on his second lap and I'm pretty sure his engine was DONE) but the panels were quite battered, and a number had full on body damage I'm assuming from track contact.

And granted this was an amateur race day, just weekenders having a good time, but it makes sense when you think about it: if the body panels aren't like falling off and are just a bit beat up... why replace them? Especially on some of these cars (late model Corvettes and Mustangs) they don't come cheap at all, and they'll require refinishing and you have to do your livery over again too.

Like a hockey player doesn't buy a new helmet every time they get hit, they/the team would be broke before the season was out.