Why are mechanics, dentists and doctors in the US GENERALLY crooks?

Don't give me the "cost of service", "insurance" and "years of education" baloney. Some of the techniques used are so old, fast to do and cost so little there is no justification for the cost. Peole in the US just don;t want to work unless you toss bags of money at them and STILL they generally do mediocre work. Most doctors and dentists are poorly educated in the US. Where do you get good doctors from from when the general pool of Americans are the worst educated in the industrial world. And mechanics? You don't need a license to work in the US. Any bozo can claim to be a mechanic.