Bonsoir - as a teacher, I actually find what you say to be insulting. You can't compare the quality of a teacher in a school with good discipline and behaviour with a teacher in a school that has pupils who behave behaviourally like they are zoo animals with no discipline. The crapest teachers can do well with support and the best teachers can struggle in a challenging situation.
I spent a couple of years teaching in a very difficult sink-estate comprehensive where discipline was pretty much non existant (poor SMT support) and the pupils ran riot. I had classes that had been put together as "behaviour classes". i.e. the pupils had issues which included being bottom set/had behavioural issues/were disengaged/had poor literacy skills... My lesson aims sometimes had to resort to "keeping the child in the classroom" and "completing a simple worksheet". I was threatened with a knife (on 2 occasions), sworn at daily, verbally abused, and had a whole host of other issues to deal with that I won't bore you with. I was lucky if I got to teach for 10 minutes out of the hour without dealing with behavioural issues. I left thinking I was a shit teacher who couldn't control my class and seriously considered finishing my teaching career there and then.
The following term on supply (because i quit without a job to go to because I though I was so bad) I was lucky enough to teach long term at the local "Ofstead Outstanding" school, where discpline and respect are hammered into the students. The first day I taught there, I was so shocked that the pupils did what they were told, my lesson ran short by 20 minutes, because I had "allowed" for behavioural issues and I didn't need to, because for once, I could actually teach the pupils properly. 2 weeks after I started, we had an Ofstead inspection where I got graded as "outstanding" and the inspector actually commented on how much she enjoyed the lesson and learned something new. Clearly I'm not that much of a shit teacher, because I regularly get head hunted by the local "good" schools when they need long-term specialist cover.
Until you've walked in the shoes of a teacher and dealt with the issues they deal with on a day-to-day basis, including teaching children, then I suggest that you look a little less critically.