I think, in Britain, real, racist violence, actual bodily harm, is rare, these days. Acts of deliberate racist cruelty and persecution are less so but are still unusual and unrepresentative of popular opinion. Both are voluntary acts of personal choice and not of state policy, either, even when perpetrated by servants of the state, such as police officers.
When they do occur, they seem driven by a desire for thrills and power. Targets are chosen on tribal lines, those identified as “other”, allowing for a “group-think” environment of mutual encouragement and shared responsibility. Fear and disdain are also being directed towards them. These are emotional rather than rational motives. People don’t come to the reasoned and sober decision that it is their civic duty to shank some black kid outside a nightclub on a Friday night. Disinhibiting factors like alcohol (and, possibly, testosterone) often seem to be involved, as well.
Emotions are personal drivers. Overt racism is an excuse to achieve the personal goals of power and consequence – it might as well be homophobia or misogyny, or transphobia. It isn’t necessary for the rationale, or the excuse, to be passionately believed in for someone to become a target. All that matters is that there is a way to single them out. Persecution can be a much more off-hand and unimportant thing for the perpetrators than for the victims, who may feel the impact of it for the rest of their lives. That’s part of its injustice. Someone who punches you in the face for being Asian may not feel race is an important issue in their lives or societies.