There's no doubt IMO that racism and bigotry must play some role in all these false convictions, but not the primary cause. I believe that the real reason conservatives don't care about law enforcement abuses is entirely political and partisan. As in, law enforcement generally votes Republican. And as long as law enforcement does that, and targets their abuses at demographics that largely don't vote Republican, then conservatives don't care. In fact, many of them applaud it.
A good example of this from the converse perspective can be found in conversatives' well-known hatred of public education, because teachers generally vote Democratic. Then suddenly, the same conservatives who don't care one bit about law enforcement fabricating evidence to generate phony convictions which strips citizens of their basic rights, or law enforcement making $200k+/year (with OT) while double-dipping full lifetime retirement benefits for 10 years before they actually retire, will freak out over teachers pushing 'liberal indoctrination,' making $60k/year with a masters degree, and how teacher's pension benefits are going to bankrupt the same PERS funds that they no objections to law enforcement double dipping from.
IOW, all political tribalism. And sure, racism and bigotry play a role in all that, but focusing on those misses the bigger picture.