My guess is 911,939.
/patsselfonback
Do still want that car, though.
So maybe you are partially right.
Um. I think you might be forgetting something about how the car industry works. The reason not to is simply that there is a multi-billion dollar industry built on the fact that most people are in fact like your mom and are willing to pay someone a few hundred dollars to diagnose and repair things for them.
And for the small, small minority of people who really want to avoid the mechanic's garage, you can, as you say, buy your own reader for a couple hundred bucks...as opposed to restandardizing the way an entire industry makes its products.
Cuz, ya know, that's so cheap.