Plus, is speed of application even a thing most nail salon customers care much about?
I don't know many who use them, but the ones I know who do consider it as much a recreational activity as anything else. They like the social aspect of doing it, as well as taking the time out to pamper themselves. They're not just getting their nails done.
Cheaper? Not even close.
I'm sure there's a high-end market for this quick paint job, but its not going to disrupt the millions of nail salons around the world.