The thing is that in most cases we aren't talking about the military or the airlines, or even high school. The instructor generally doesn't have the power over the student that some seem to think they have & that some students seem to be willing to give them. I belive that this sort of crap also goes on in the music lesson business as well. Who knows where else. Maybe it is a hangover from the only learning environment that most people have experienced, i.e. school.
What people need to remember is that we are talking about someone walking in & putting down their hard earned dollars for a service. The flying school & ALL it's staff should be bending over backwards to keep the 'customer' happy, so that they can keep the ongoing business & also get any referrals that the customer might be able & willing to give.
The trouble is that most students seem to forget that they are the consumer & therefore have the power to take their business, money & word of mouth advertising elsewhere.
Business must be good if flying schools can afford to 'tick off' customers with this sort of behaviour. That being said, most tradespeople seem to operate the same way these days.