(Richard here... I have also seen this abusive behaviour, not just in Japan, but in other places as well. At the Kanto High School Championships in January I saw a father wildy hit his son for losing the finals for his team kumite division. Arakawa Sensei and I have discussed this in detail, and he is absolutely against any abusive style of disciplining/coaching/motivating. Which is why I support Arakawa Sensei's positive way of teaching karate, and it obviously pays off for him with so many students staying with him. For sure nowadays karate in Japan is seen as safe and for the most part it is. Maeda Sensei, the former national coach, said the confusion between proper discipline and corporeal violence was blurred in the past, but this is pretty much gone from karate and it only lingers now in some parts of sumo. Arakawa Sensei also confronts other instructors when they're out of line even if it has nothing to do with Shiramizu because he hates the unnecessary macho aspects of budo.)
Warming up in the holding area.
Shiramizu after the tournament (Picture courtesy of Arakawa Sensei's blog).