There’s plenty of people that have been gradually convinced that wouldn’t have agreed before. Constant awareness creates progress. Each police brutality instance is nuanced in different ways and presents different evidence that can sway someone’s opinion. There’s also a huge cohort of people who are on the fence or generally indifferent. Maybe someone who didn’t feel compelled to go out and vote will be pushed enough to one side to actually go fill out a ballot. If you think minds can’t be changed then how come George Floyd was such a large event? Police have been shooting black people forever, and in the spotlight for decades now, if you can’t change minds then what suddenly was different with that one?