American teachers aren't held to low standards. Honestly the standards aren't that low at all, and it takes at a minimum a four year degree with a credentialling program.
Thing is culturally we have very little respect for our education system (and pretty much every public service in the country), couple that with the fact that most of our youth in public schools are either blacks or mexicans, public schools are generally violent and toxic environments.
I tried being a teacher here in America, but the only places actively looking for teachers were in black majority districts... which I tried, but it wasn't worth the violence and inability to do anything.
I've taught a handful of white classes, and honestly it's like night and day. The kids listened and had a decent amount of respect for the teacher. Not quite to the extent that high trust Europe has, but frankly I finally found something I liked about the job.