I think there's also the issue of where do kids have to go hang out anymore?

By and large, malls are dead/dying, and some don't even allow unsupervised kids anymore.

Movies are expensive. Restaurants are expensive. Concerts are expensive (if you're lucky enough to live somewhere with easy access to concert venues, if you're in the suburbs you probably have an uphill battle trying to convince your parents to let you go wandering around the city unsupervised to go to a concert) Arcades basically don't even exist anymore.

They can barely even go hang out in a park without being harassed by some Karen or the cops, and of course parks usually close at dusk and kind of depend on the weather being decent so in many places there's a good chunk of the year where parks are undesirable.

You can hang out at your friends' houses, but depending on your area there's a decent chance that they may be in walking or biking distance so no need for a car, and if you're just going to be hanging around the house, not a big deal for Mom or Dad to drop you off/pick you up, not like you're going to really need a car while you're there, you got nowhere to go anyway. And of course we get some parents these days who are really weird about their kids going over to other people's homes, which leaves staying home and hanging out online.

About the only thing I can think of that I used to do as a kid that might still be accessible for kids and might necessitate them having their own car is to go hang out at the local comic/game shop to play magic, d&d, etc. Because most of them are pretty cool about people just coming to hang out, but even that could really be a "hey parental unit, can I get a ride?" kind of thing.

Plus, if you have a tight group of friends you always hang out with, you may only need a couple drivers. Even going back to when I was a teen/young adult, a lot of my friends didn't have a license and many of them who did didn't have their own car or couldn't count on borrowing their parents' car. I know the core group I hung out with was probably around 6-10 people, and one other guy and I did 99% of our driving whenever we went to do something because we were the ones with cars. Probably up until I was about 23 I spent a lot of time picking friends up and giving them rides places because I had a car and they didn't.