It's really sad that some gyms will hire anybody with any certificate from anywhere as a personal trainer. A lot of those guys don't know jack shit.
As far as if this is a career move or not...it could be. Some guys in LA make hundreds an hour. In Austin a G4 trainer at Gold's gets paid $85/hour (of course Gold's takes a good bit of it away but he can easily take his customers with himself and quit).
i would think they still have the PTs sign something saying they cant take their clients, but I havent seen the docs in years and years. of course they would need to follow up, but ive seen first hand that the gym calls their previous clients that were using PT services and if any of them screw up and mention they went with that PT, oh oh.