because 20 years ago that wasn't the case, so I doubt it is now.
The way it used to be was the car had to meet the crash/emissions/dot standards of the day it was built or imported.
So a 1950s car for instance, didn't have to have seatbelts. That was changed, at least in Oregon. Now the only way around THAT is to get a "special license" which is only valid for going to and from events, or places of repair. The "special license" gets abused a lot though, and enforcement is pretty lax. One of the guys I used to do car shows with had a "special license" on his Model T.