At least in MN the way it works is that vehicles over a certain age can be registered as collectors vehicles and get special lifetime collectors plates. If you register a vehicle as a collectors vehicle then it doesn't need any updated emissions or safety equipment. But at the same time it is illegal to use a collectors vehicle for daily driving. You are only permitted to drive it to/from shows/events and to take it on occasional pleasure drives. If you get caught making a grocery run with one then you get fined, the plates impounded, and you could even face jail time.

This seems to work out pretty well here. It's pretty uncommon to see these vehicles on the road outside of big events. And it doesn't require owners to modify their classic vehicles when many pride themselves on keeping these vehicles as stock as possible.

Edit: Also ethanol isca very bad idea for these vehicles. Firstly the seals and hoses on these vehicles are not designed for it so it destroys them, as someone else aluded to. But more importantly, these vehicles aren't being driven regularly and ethanol is not stable to leave in the vehicles. When it ages ethanol breaks down into a varnish that covers everything and clogs the hell out of things like carburators. That is the reason that you want to use nonoxygenated gas (no ethanol added) on vehicles that aren't driven frequently. Ethanol is the main thing that makes gas go bad. If you don't have ethanol in there then the shelf life is extended dramatically. If you ran these vehicles on ethanol you would basically be requiring people to drain and dry every fuel carrying component whenever they wanted to store it (which should be often if you don't want them daily driving them).