So yes, Americans are vastly more tolerant of police violence (to say nothing of stratospheric incarceration levels) than the British - mainly because black people are so disproportionally targeted in this country.
Indeed, among America's more reactionary elements, the unrestrained use-of-force and incarceration policies behind these figures are vehemently defended, as they provide an effective way to enforce a racially-determined class structure, even in the absence of the Jim Crow laws that performed this role until the late 1960s.
However, none of this would be acceptable if the police were equally harsh with everyone. Indiscriminate oppression is much harder sustain in the U.S. In that regard, we're quite different from the UK, where the "if you've done nothing wrong you've got nothing to hide" attitude is far more prevalent (it's a fixture in comment sections of British news sites, whereas American sites see it crop up far less frequently).
The fact that mass surveillance doesn't easily square with the more "acceptable" (read: racist) forms of police abuse in America is why Americans are far more unified in their opposition to it.