Couldn't they at least drive to the rioting and have policemen clear the roads they need to get through or summat? I simply see no reason why the police would forego arresting rioters and looters in favor of attacking peaceful protesters. Clearly they did, but... why?
Because the rioters weren't there, and they have to charge headlong and attack
someone!
Situations like the ones the police are in are impossble to know what they're like until they've actually been experienced. Sitting at home, it's easy to say "go for the ones doing dangerous things and leave the rest alone", but in practice such instructions are ridiculous. I've been in situations a bit like these, but on a much, much, smaller scale, and even instructions like "go for the ones wearing red shirts and leave the rest alone" become incredibly hard to follow in practice. I wouldn't be able to explain why, though: the experience is incredibly hard if not impossible to communicate.
I've been in riotous situations. I saw people tipping over trucks, and setting them on fire, i saw the security and the rioters, the people throwing stuff, the people in black body armour... And I managed to not attack people sitting down singing out of some sort of confusion.
Also it's extremely easy to tell the difference between people sitting down and singing and people smashing and looting and burning things. Aside from that you're implying that police having
any semblance of reason, tactics, restraint, or anything is "riduculous" in these situations... if that is the case then they are only ever going to make things worse. You're basically saying that once they're in that situation they're going to (and should be expected to) behave like the worst of the rioters, attacking anyone in sight because they have no idea what is happening, and can't be expected to follow even the most basic of orders, or show any kind of restraint.