Holy shit those cops are tolerant. Those guys would have been shot and killed here in the states waving a knife around in public.
This is very true. Often I see cops in yelling matches with people who would simply be arrested while in the States.
Another thing the cops will do is come around with a video camera and take video of small infraction. (I've seen them do it for people begging in forbidden areas and one restaurant owner for putting his tables in a public area.)
I don't speak Chinese well enough to understand what they're saying, but it really surprised me. I just figured they would at least be as hardcore as American cops, considering the judicial system is a farce.