A lot of things come into play here.
Equality under the law
Practicality of action.
Behaviour of the crowd
Regarding the Rangers response, the police had absolutely no chance unless they brought in water cannon, armoured cars, heavy force, etc. I recall Boris bought water cannon for use in quelling riots in London but the furore was so great that they couldn’t be used.
Regarding last night, the problem was the ludicrous Covid laws which are a stain on the fundamental freedoms of citizens of this country. Having seen the pictures, there didn’t appear to be any public order problem, so, in that case, the police actions were heavy handed. However, they are tasked with upholding the law, so they are left in an impossible position. What do they do? It’s all very well ranting and raving about police actions but it’s the politicians to blame for putting them in impossible situations.
People like myself get annoyed with BLM , antifa and statue toppling demos but it’s not easy to come up with a solution that satisfies upholding the law, allowing peaceful demonstrations and addressing the practical problems facing the police in dealing with these events.
No easy answer