My wife teaches an entry level course that all community college students at her school are required to take. This course is supposed to teach them about learning techniques for success in the college environment. She usually has to fail about 2/3 of them because they don't do any of the assigned work. The students can't believe it; they're shocked.
Because teachers are not allowed to fail them in several of our local public school districts. All they have to do is make attendance and they get a D at least. Some even get angry at my wife for failing them; threaten lawsuits, etc...
Of those that fail, only about 30 % stay in school, the rest drop out.