Ok, so they have to
practice crashing, but do they have to do it at a busy airfield?

Having seen elevators and rudders thrash about from the
propwash of helicopters at several fuel pumps, and
having seen these many autorotations in my flight path,
I am consistently impressed by the experienced
helicopter instructors who use common sense and do these
things elsewhere. Some use "closed" airfields, others
suck up the extra cost and get their gas out of the truck.

I personally take my power students to barren airfields for landing
practice, even though it costs $$$$s to get there. I know quite
a few other instructors (including helicopter) who do the same.
Good for them!