It's more efficient to have guns that don't need to be picked up and moved while running. Dangerous work, especially when on a steeper trail. It's also a lot quicker to resurface after a thaw/r*in when you don't have to move guns into position, just light em up as soon as it's cold enough.
I've seen plenty of trails opened without grooming where they used tower guns. Hunter and Mound Snow do this pretty frequently.
Fan guns cost like 30,000 a piece, but spread the snow out very well, so no whales to groom out.
I've lived in New York my entire life.