There are fewer anti police riots in UK, because UK is much more effective at catching and prosecuting rioters than US. In US, rioters enjoy extreme leniency. Only a tiny fraction of 2020 rioters have faced any justice at all.
As for police killings, you are comparing an event that’s extremely unlikely to happen with an event that’s multiple orders of magnitude more likely. Speech offense prosecutions in UK are more common today than political prosecutions were in post Kruschev Soviet Union. The only reason UK has fewer political prisoners than Soviet Union had is that the sentences are shorter and typically non-custodial.
As for police killings, you are comparing an event that’s extremely unlikely to happen with an event that’s multiple orders of magnitude more likely. Speech offense prosecutions in UK are more common today than political prosecutions were in post Kruschev Soviet Union. The only reason UK has fewer political prisoners than Soviet Union had is that the sentences are shorter and typically non-custodial.