Again, think real world and not theory. Those other levels. How many people fit in a stadium? 20K? Kinnick is 60K. Lots more support staff needed when you're triple or quadruple the size. (not to mention those schools pay to host playoff games so there must be a demand for them)
And pro stadium do pull it off, in one or two days, but all those dates are set in advance. It's not just a surprise. Those teams, workforces, know the possibility a year in advance.
They also pull it off on a short turnaround, such as the wild card. But, some logistical things to think about here. At most you are going to have 3 or 4 teams facing a wild card home game possibilty. So they can start getting the logistics in order a couple of weeks before. You can also build it into contract and hold the staff on call so to speak and that one extra game isn't going to cost you and arm and a leg cause its only extends the overall contract by a couple days.
Not to mention every pro stadium even in the NFL is smaller than most colleges. Also you don't have to deal with things like student tickets, bands, etc at the pro level.
College football is a bit different, do 120 teams build contracts for 8 or 9 weeks instead of 6 or 7? How much more is that going to cost them?
I think the issue here is many don't understand how hard and complex it is to put together a Power 5 football game. See if you can go behind the scenes and find out. It's a hell of a challenge and way more complicated than even a pro event.