Fact: Aeroplanes cost x per hour to operate
Fact: There is no such thing as cheap flying, and lower hourly rates are often made up for by all sorts of hidden costs.
Fact: Many operators save costs by ripping off their staff. Not only in the rates they are paid, but other entitlements such as superannuation.
When the wannabes are shopping around, they always ask what the hourly rates are, and as curtissjenny has rightly said there is more to it than the hourly rate. There are things they don't see initially, the quality of aircraft, maintenance, service, infrastructure etc. It simply isn't possible to run a flying school efficiently and safely if you are operating below cost.
hdaae, I believe the majority of instructors give their very best to their students. But there is no doubt that those who feel they are not being treated well by their employer may be tempted to have a good bitch about the boss with their colleagues, and this will affect the quality of their work.