I think colleges care too much about your past academic performance. I believe that if someone truly thinks they have the potential to pursue scholastically in a specific college than they should be granted that right. Especially if they're willing to pay tuition. Colleges are too afraid about ruining their reputation even though they don't know that some people can change their view on education and to consider if they're worthy of becoming a student at that school could cost them a great loss of a possible outstanding scholar. When we enter high school we are 14 years old and haven't had the time to fully mature not only physically but mentally as well.
College is a higher type of learning. Unlike public school, which prepares you for college, you have to be ready to buckle down and study. You have to be able to afford the right to move on in your education. You have to pass entrance exams, and you have to have had decent grades in high school.
Colleges have a vast majority of different things people can learn. Some colleges have more specific classes they give, but that is helpful to both students and the college. In those specific courses they can focus just on what they are going for and get through without having to learn or take classes that won't be applied to their career choice or major.
It is not inherently difficult to get into a college, however to get into a notable college requires more effort and better grades. The selectivity of colleges depends on the type of education you will receive and also the cost. However just because a college is selective does not mean the education will be good. Some lesser known colleges can have an education that can exceed a top tier university. It is this snobbishness that needs to be abolished.