[staticshock]

Experience does correlate strongly with current ability, but it correlates much more weakly with potential ability.

There's no college out there that requires "5 years prior job experience", because the relationship between college and student is very different than between employer and employee. Employers look for current ability. Colleges, on the other hand, look for future ability, the indicators of which are significantly more speculative.

[yummyfajitas]

There is at least one college which requires demonstrated skill (albeit not $N years of experience).

http://www.juilliard.edu/admissions/entrance/index.html

According to my mother (a musician) most music programs tend to require prior experience. The rationale is a stronger version of what forensic said: anyone serious about music would have already invested effort into learning how to play. The same could be easily said about CS.

[forensic]

Every college looks at SATs and GPA, which are nothing more than measures of current ability. SATs measure current ability† in math and language. GPA measures current ability in all the subjects. Oftentimes an applicant can get special consideration by proving their interest in the subject and having some experience - for instance at science fairs. Or you can go talk to the professors of your particular subject and if the professors are impressed by your interest in the field they give special consideration. The best predictor of future interest is past interest. And anyone interested in computer science will have experience with it outside of the classroom.

†I know, theoretically they measure potential - but c'mon we all know that's bullshit. It's so easy to either raise or lower your SAT scores through study and experience.