How come higher education is prohibitively expensive?

Why is the cost of education so bloody high? If this is a mechanism to screen people out and make it accessible only to a certain group, why not introduce entrance examinations (and I don't mean these standardized crap exams from ETS- this is just as much a money making racket, and they only test how well you are able to take tests, not what you know and would be able to apply in a higher education setting) as a means of screening instead? This way, bright individuals who are academically qualified but don't have the money to go to school would not be hampered by the financial aspect of it, and would be able to attend based on aptitude and academic promise. Why not require potential students to do a day of testing in the subject area of choice and let that be the deciding factor as to who attends college, instead of putting it out of most people's reach with horrendous tuition rates and bogus, suspicious fees that pop up on bursar bills?