The Kings certainly are widely used in the US. Their success has come from finding ways to help people pass written tests with a minimum of effort.
That and the two page colour adverts in every issue of every flying magazine. And I think they give away an aeroplane every year or so.
Mr Hat, as soon as you asked what FBO stood for, I couldn't remember. They make their money selling gas, running a flight school, maybe a spot of maintenance, perhaps a small pilot shop, maybe a restaurant, also hangar rental if they have them. They can range in size from a little dusty office with a couple of old timers hanging about to a sleek executive terminal with lots of staff, car hire desk and rolled up red carpets for the visitors.