>Imagine if the police were trained to remain passive even when struck.
Tell me how much it would cost to train a police force to that level of self control, and to be able identify, in a split second, if the person is attempting to do serious harm to you or is just blowing off steam. Once a person is close enough, there are plenty of blind spots to pull a knife out of.
>the crowd would turn on the violent protesters and protect the cops
Crowd psychology overrides individual identity.
https://en.wikipedia.org/wiki/Crowd_psychology
https://twitter.com/TyreeBP/status/1256813343764918272
Granted, the number of people is ~100x different. Still, examples like the tweet above illustrate that the needed 'self control' has existed within about a pay-period or two.