I have been corresponding with the sensei of the karate dōjō in Central Oregon I took my son to while we were there.
As I noted here in my State-side Observations below, I felt that teachers/instructors in America (the ones I had observed, at least) were . . . shall I say gentle? with the students. Lessons were shorter, less physically demanding than what my sons normally have to deal with in Japan. Teachers spoke in calm voices, never yelled or criticized harshly.
In Japan (again in my experience), Spartanism rules. At my sons’ dōjō, practice can sometimes go on for two or three hours. Some kids go four times a week throughout the year. The air conditioning is rarely used in summer; the heater, only sparingly in winter. The kids spar and spar and spar, sometimes to the point of becoming black and blue. Yet, when the Japanese sensei praises a student, it’s genuine praise and the kids take great pride when they do a good job. That is often the first thing my sons tell me when they come home from practice: "Sensei-ni homerareta!"
When I mentioned this to the karate sensei in Oregon, he replied that American kids wouldn't be able to endure such training. "It's a difficult balance with east vs west philosophy in karate training since our students have western upbringings. I was raised training on the eastern methods and greatly appreciate the value but most Americans wouldn't accept it. There lies the quest for balancing the two sides."