Slightly off-topic, but what's the reason that Americans all tend to line-up at the drive thru? I was in LA, there was a huge line at the drive thru, so we parked, went inside and got our orders really quickly.
The comfort of still being in your own space. For example, listening to your own music, no excursion for your kids to belabor, precisely don't have to park and get out.
Yeah, I think I would rather wait 10 minutes in my car than 5 minutes in line. I'm sure other people may feel differently. And something about the drive-thru still "feels" faster, even if it's not. I think it's just the idea that you get to pull out and be on your way after you've gotten your food.
At McDonald's at least the drive through is prioritised over walk ins. That said if the queue is still long it might be quicker to walk in. But inside if orders come at the same time they do the drive through order first.