What's stopping you from lying and saying that all your classes have finals on Friday? It seems kind of stupid that they'll deprive you of a dorm you paid for because of how your schedule is laid out…

most schools have some sort of database with everyone's course registration and often finals follow a regular schedule that can be derived from the student's course enrollment. I don't know why they even bother to make students tell the RA. they could just send each student's exam schedule directly to the RA and require some written notice from the professor to document exceptions.

another question is why it even matters. what are they going to do with the fraction of dorms that are empty after the first day of exams that can't wait a few more days?

They wanted students out so they didn't disturb the students that were still studying.

And the 180 other days the students were there, distracting eachother? Midterms? What about students that have their finals early, just have to have a disadvantage in study environment?

I think the idea was that once students are done with their finals they're going to want to celebrate and relax by throwing parties or drinking and it's best that they don't do that in the dorms and keep people up all night. Personally, I would just prefer students have single dorms so they don't have to worry about a loud roommate.

sure, but if it were really important to res life they could at least require an email as evidence.

Everyone 100 level class had their final time set by the registrar.

My university does this too, and that doesn't stop professors. They just have to find their own place to have the final.