My personal memories:
I was a kid at the tail-end of the drive-in, born in 1967, so I never went much with just friends-- there was always an adult driver.
The most salient points I can think of, though, is that cars used to be a lot bigger, and theaters used to be cramped like the coach seating on airplanes-- and sold out, or close to it, even for films that had been there a while.
OMG, were drive-ins more comfortable than theaters.
And don’t forget, there were tons of convertibles still on the road then. You didn’t watch through the windshield, you watched over it. If you weren’t in a convertible, but were a literal kid, under about 12, your parents would let you sit on the hood of the car.
People talked, kids and teens ran and walked around, and no one cared much.
No one cared about tinny mono sound, either, because the sound in theaters was Dolby digital Surround Sound, not even close. It wasn’t always even stereo, and even if it was available, not all theaters could reproduce it.
Several things killed off the drive-in, it wasn’t just one thing, but they all munched at different aspects. One was the vast improvement of sound in theaters; another was cars getting a lot smaller, plus seatbelt laws, so you couldn’t go to the drive-in with six minors in the back of a pick-up, or the rear seat of a convertible with two seatbelts; another was home video-- VCRs, then DVDs, then streaming services-- many of the things drive-ins afforded: bring the kids, go to the bathroom without bothering everyone in your row, talk to the person with you, stretch out-- you could now do in your own home. And drive-ins tended to be on the edge of town, where land and property taxes were cheaper, so it was a longer shlep then the video store.
Yeah, they were revived during the pandemic, for the reasons others have posted above, and didn’t outlast it, for the objections raised by the OP.
There might be some walk-through history aspect of going to a drive-in for young people, for whom churning your own butter, and operating a record player are equal curiosities. And I suspect for people born before the Bicentennial, there might be a bit of nostalgia that would draw us to a drive-in once every decade, especially if it showed something we might have seen originally in a drive-in. Not me personally, but some people. When I’m feeling nostalgic, I get a Tootsie pop.