Thats because as much as people would like to believe its not a professional job.
The nearest thing you would get is a car driving instructor for PPL or HGV instructor for CPL.
Once you get away from thinking flying is special. Your just into employing any form of trainer be it IT, health and safety or any of the other vocational training out there. And it doesn't follow with flying that you are good at the job then move sideways into training because you have been seen to have a knack for it. Your just stuck into it when your experence level means your pretty much clueless.
The bit that instructing falls over with is that the very large majority of instructors its a means to an end to getting further up the career ladder which to be honest at the moment is broken in the middle.
Alot of people also forget is that the school is the sum of its instructors. You get even one that isn't up to grade and it pulls the whole place down very rapidly. Any falling out with the boss with a good/bad instructor that gets on with the punters also means a real hit to the cash flow. Which is why no doudt the OP got the boot as soon as they spoke up. The boss will want them out the door ASAP so that the slagging them off behind their back can commence to try and damage limit the fall out.
You get quite a few that have the gift of the gab with the punters but are utterly ****e at doing the job. This then bites you later when folk are taking 90-100 hours because all the instructor is interested in is getting 1000 hours in thier log book and the school reputation gets pulled down.