despite this being something practically everybody wants, the fact that it hasn't happened is not a coincidence and speaks to the power of police unions/guilds and their lobbying arms. outside a few toothless instances, those groups are extremely good at reframing these attempts and mobilizing their bases to vote against the broader public interest.
it sucks.
> despite this being something practically everybody wants,
No, everybody does not want police accountability. Half the population will fall on a grenade to prevent that. They know that the purpose of the police is to keep the undesirables in line, and they never envision that they will ever fall in that category.
The brutality is the point for them.