Because there is much more demand than supply in the US for a college education. Going merit based is not that simple. If you have 1000 open seats at your schoo

Because there is much more demand than supply in the US for a college education. Going merit based is not that simple. If you have 1000 open seats at your school, 50,000 students apply and 1500 of them all have perfect SAT scores, how do you choose who gets in if it's entirely merit based. What makes this perfect SAT score different from that equally perfect SAT score? If everyone looks the same on paper, you need something extra to stand out. That's where extra-curricular activities come in. The other issue is programs. If you're a school with 1000 open seats and 100 of that is music, you're going to have to drop some very science-smart students to make room for music-smart students.