I suspect car longevity has also been a factor. During my lifetime cars had 5-digit odometers. Cars now regularly last 200,000 to 300,000 miles. Oil changes have gone from 3,000 miles to 5,000 or as much as 15,000. Even more in a hybrid.

Those repairs that are necessary are harder than they used to be. I recently had to have a headlight bulb changed professionally because I just didn't want to dismount the wheel well mud guard. Some, I've heard, require you to remove the bumper.

But I think a lot of those service bays just stopped seeing as much traffic as they used to.