Parking slot sizes have not shrunk, it is the cars parked in them that have grown bigger. This is well-documented.

I don't believe that. I've seen it myself when a store will restripe their lot to squeeze more parking in. I never had to grease the sides of the car to park it in the 70's.

That store may well have been the exception, but I'm still curious: what process did you use to come up with the idea that the restriped slots were smaller?

My car's fit in them.

You have a car from the '70s? And this is not when there are more modern cars next to it that make it feel more cramped because they are bigger?