Most Americans haven’t interacted with the police or their trust would evaporate. Pretty much every single one of these institutions has the privilege of being absolved from responsibility.
When I was a kid a cop pulled my dad over for running a stop sign with me, my mom, and my great aunt in the car. We all concurred that he did in fact stop, he argued with the cop and got a ticket. My dad is white as they come, and any time I bring up interactions with cops he says you can't trust them... Still votes for Trump, and he's a Christian Western chauvinist. There's no accounting for political opinions in America.
I know a lot of people in rural communities absolutely think cops are practically useless, hell we had a case here that a police dept in a small town 10mi north of me got busted for corruption this past year. And everyone pretty much cheered that they got busted because they had really bad rep.
But these people also seem to think big cities are crime ridden hell holes and cops are necessary there.
My brother got robbed at gunpoint and for weeks he'd bring credit card statements from local gas stations where the stolen cc was being used, back to the police and he was too stupid to tell that their "you should be a detective" was being said to fuck with him.
I saw a poll they did where they asked parents if they thought public schools are good, and most people say they're bad. But when they followed up and asked specifically about the public schools their children go to, they have high opinions of them.
Same shit with crime. People think crime is off the charts everywhere else, but their community is fine.