My two cents - USA colleges and universities have been known to use undergrads to teach labs and grad students to teach labs and even full courses. Those teachers have ZERO formal education instruction under their belts. Some utterly suck, but others do a fine job and qualify quite well as teachers in my book. I've also seen properly licensed and experienced teachers, some at very high levels of certification, who should never have been allowed near any classroom.
Teaching is an art, not a science. Some artists need to go to art school to become any good. Others are already good and can be improved by education. Others are good enough that they shouldn't be messed with. Some people can be trained for decades and still aren't good artists.
I'd also like to say that I'm deeply and bitterly disappointed not to have been dragged away and aggressively molested by any Chinese teachers or students.
One time a VERY hot Chinese teacher at a middle school I was doing some classes at asked me to come to her apartment to "lie down." I was completely taken off guard, so instead of saying "OH YES!", I said "WHAT?!?". She replied, "Come to my apartment to lie down with me and my husband." My reaction, "
WHAT?!?!!?" Then she said, "We always take a nap after lunch. You can lie down on the bed in the guest room."
And, just to creep out those who are easily creeped out, the last time I checked, the legal age of consent here in the Big Silly is 14.