The police don’t charge at will mate an order has to be given based on the threat level and the actions of the crowd.
The person giving the order will be sat miles away monitoring a live feed, with an acute awareness that the whole thing will be on social media in seconds and all that that brings. The whole situation will have been evaluated based on restoring order and regaining control of the situation as quickly as possible, before it gets totally out of hand.
It’s not just one of the coppers shouting “ charge “ and all the rest piling in.