I think your parent made a perfectly good point. Going into the store is a whole lot less pleasant than staying in my car and waiting a couple extra minutes in an environment I enjoy.

If I’m in a hurry then yes maybe I can shave a few minutes by going in, but if I’m getting fast food I probably don’t feel like interacting with people, and listening to crappy piped music while standing in an artificially lit corporate chain restaurant waiting for my order.

Don't disagree with your generalization of the interiors of fast food restaurants, but I can't say I prefer the interior of my car either.