Private entities pay for cops all the time, this isn't as radical as it seems. For instance, when I used to be involved in student government we knew that part of the cost of having a big event was having to pay for the mandatory number of cops who had to be there. The city knew that college students in large groups were trouble, and they didn't want to have to foot the bill, so they passed an ordance that required us to foot the bill for any event with X number of people expected (I forget what X was).
I'm pretty sure the same thing happens with some concerts, sporting events, etc.: the municipalities don't want to pay, so they make the entity responsible pay for it. Then again, lots of stadium owners have cozy deals with the city, which probably avoid this sort of thing.
In any case, the only unusual thing about this that I can see is that's a full-time gig.