All you have is your own experience. I have experience of over 30 years, during which time I've known the exemplary teachers you refer to being beaten up by out of control students. Some teachers will experience the joy of teaching but most I'm afraid to say are just surviving.I know you'll find this questionable, and I know there are bad teachers out there, but the fact is our society is crumbling, there are no role models other than Mr and Mrs Nobody,so many one parent families, too many additives, mobile phones, crisps, energy drinks, Porn is easily accessed,violence on the TV, no areas outside in which to play and even if there was Mothers would worry about Peadophiles, war everywhere, Corrupt Politicians, Antisemitism, Anti Muslem, no Religion, no guidelines..just vacuous parents who don't have a clue about boundaries. BTW I'm not refering to the majority, but the minority, and they are ever increasing.
from the article: Israeli teacher's blog: I'd like to spray class with machine gun