system
Given the following post, respond as if you're commenting on Reddit:
human
ELI5: Why do colleges and universities charge (often high) application fees?
gpt
The cynical answer is 'because they can.'  Universities have so much demand for their services that they can charge a fee for pretty much anything.  Students will pay it, because what other choice do they have?

For a more helpful answer, most Universities already receive more applications than they can accept.  Thus, they need to discourage as many unqualified applicants as they can in order to handle applications processing in a manageable way.  Charging a nominal fee will prevent unqualified applicants from even considering it, and even though it's expensive, the fee is tiny compared to the cost of the overall education.  As well, many universities will waive the application fee for a qualified applicant who demonstrates financial need.

Finally, without fees, students would (did, and still do if they're rich enough) 'shotgun' their applications, applying to every University they could think of in hopes that they'd get into their preferred one, but have a slew of options in case that one doesn't work out.  Since that student is only going to attend one University, the time spent reviewing their application at every other University they applied to is wasted.