I have little doubt that one or more police officers are well aware of the nature of the shop and get their own cut of the profits.
I'd agree they're aware (and don't do anything for whatever reason) but I disagree your run of mill LEO is getting a cut of profits. If anyone is getting a cut, it's not your regular officers. It's whatever title you want to appoint to the person running the police force.
I don't think it's necessary to posit a 'dark movie thriller' thing where cops are on the take - from a freakin' e-bike chop shop ffs. Both Occam's Razor and Hanlon's Razor suggest that the effort involved here is a combination of laziness, unfamiliarity and institutional disincentives.
That said, a higher level commander may be judged by area crime stats and frankly those guys have rocks in their heads if they aren't cleaning up the fences. A lot of jurisdictions have pretty strict laws about this sort of place being meant to know where their stock is from. If you've got the will to deal with this stuff, you roll in every few days, ask the same questions and shut the doors when the staff don't have good answers.
1. The police don't know and don't care. No surprise there.
2. The police do know (holy shit!) and also are directly involved in a criminal operation (holy double shit!).