What is up with college in america?

why is it that america is the only country in the world that requires 4 years of college in order to go onto medicine, engineering, or any other decent and well paying job?? every other country in the world allows a high schooler to directly go to e.g. medical school, engineering school. i've heard that its really just a money making thing because most of college graduates say that they don't remember 70 percent of the things they learned in college, and only remember what they did to do their job. what's your opinion?