In my area there are dozens of people idling for 10-15 minutes in the Starbucks drive through even though we have a municipal "no idling" bylaw to reduce emissions. The line is so long it interferes with traffic on the street. It also seems like sitting in your car inhaling CO from other people's tailpipes for 15 minutes is bad for you?
Many of the local fast food places have also switched to "drive through only" at night, which means they can get away with not having public washrooms (which are required by law when serving food). On a recent road trip my friends and I spent an hour driving place-to-place at 10pm on a Saturday trying to find a place to get a late dinner and use the toilets.
Drive-throughs also create an insane, perverse incentive for customers inside the store. Between online ordering and drive through staff are completely ignoring the actual walk-up counter traffic, because that's the only traffic where corporate doesn't track service time. I've stopped going into a lot of locations on impulse because I know they'll be understaffed and you have to book your shitty lunch 20 minutes in advance with an app. On the flip side these companies are doing promos with free delivery, where a taxi drives a burger to my house for no extra cost.
In short, I understand why companies would like drive throughs - they can have fewer staff and they game laws around the indoor dining area. Their end game is probably drive-thru only ghost kitchens with no indoor dining at all.
On a personal level I don't understand why consumers prefer drive-through (except for the feedback spiral of in-restaurant experiences becoming shit because of drive throughs). And on a policy level I don't understand why municipalities are permitting ever-larger double drive throughs with longer queues and shorter in-restaurant hours? It creates a hollowed-out neighborhood with no walkability that feels miserable.