I recently switched barns and I’m incredibly happy where I am now (I don’t own a horse currently), but I sympathize with the OP, based on what I’ve seen in my area, especially at hunter-jumper barns. There’s an increasingly wide gap between barns on the higher end of the spectrum, where the business model is built around showing, and lower-end barns where instruction and facilities are pretty dicey. It’s not that the instructors are evil (not that there aren’t some horrific ones), but to stay in business by emphasizing showing over laying down a solid foundation, almost by definition you’re going to be favoring certain kinds of horses, riding, and ways of riding that aren’t always in the best interest of the horse or rider. (It’s not always the instructor’s fault, of course, sometimes clients demand to move up way before they’re ready, too, of course, and instructors may feel financially pressured to keep a client.)
But the alternative can be a barn with just flat-out no instruction and substandard care and facilities. Add in the factor many barns only allow jumping in lessons for liability reasons, and that makes people even more dependent upon trainers than in previous generations.
I don’t have a horse right now, and I’ve switched to dressage, so I have way less skin in the game than the OP, but the past couple of years, I’ve kind of given myself permission to say “no” even if I know the trainer has more knowledge than me and I am (frankly) not a great rider. Even if you don’t know how to do a perfect polo wrap, it’s okay to speak up if you don’t feel the horse you’re lessoning on is sound and end the lesson. Or to leave a barn you feel is being run poorly, even if you haven’t run a barn yourself.