I think most people will wind up dismissing feedback because of how "personal" a car is to them and secondly, how much they really care about "cleaning" their car. To the vast majority of folks, "detailing" is a fancy word for "clean", and of course everyone knows how to clean. lol
It's true. Almost everyone can clean a a car, except for those people who miss huge spots because they are too lazy to overlap their strokes, and then when it is time to dry, they don't rewash those areas, they just wipe the dirt off at the same time they dry the car.
I saw my parent's daughter do that once. I told her she missed a spot and to rewash it. She was too lazy. It didn't matter to her. Of course, dish soap was used, or maybe laundry detergent. At least she used soap.
Almost anyone can clean a car, but can they clean it SAFELY, while preserving the finish and the value of the car? Are they thorough enough to clean all the crevices? That is what a detailing wash is.
Sure, you can clean a car with a brillo pad, and it's really easy to do, the FIRST time. The second time and every time after, it gets more and more difficult, because the dirt and grime are getting trapped in the scratches that they put in the finish by using the brillo pad, which only gets worse every time they clean it. It is more difficult to wash because they don't wax enough. They think the time to wax is after the car looks dull.
This is why people's clear coat fails, because it take a LONG time for a clear coated car to get dull, so by the time they get around to waxing then, it is too late.
Because people are used to waxing after they wait too long, it's very difficult to do , they loather it, so it only puts off waxing even longer.
There are other people who have the opposite problem. They wax their cars 4 or 5 times a year with cleaner waxes that contain polish, so after a few years, they have worn the paint down to the primer on the fenders.
At least the person at the car wash didn't use the widow squeegee on their paint....