As someone who is low income, the free tuition isn't actually that big of a draw. Most if not all schools at the caliber of NYU have really solid need-based aid that covers tuition.
For people who aren't in that situation, there are other schools that give full-tuition merit scholarships as well (Penn, WashU come to mind), so I bet folks in that position have more than one "free" option.
And I'm sure there are some people for whom money isn't that important. They would rather pick schools with stronger reputations, in different locations, or that were a better fit.
That is all to say, if you're on the waitlist, you still have a chance 😉