The issue isn’t that police exist. Like you said, police are necessary for government to function because agreed upon rules/laws must be enforced. Since we live in a physical world, the ultimate escalation of disagreements is physical force, i.e. violence, so in order to be the supreme enforcer of laws, the government must have a monopoly (or at least undisputed superiority) on violence. Police are the first-level enforcers and therefore exist as a group with the ability to use violence among a populace that is largely disallowed from the same. This is just an inherent fact of a governing body and I don’t think any ideology disagrees. Even anarchism is in agreement, since it’s lack of police also necessitates the lack of a government.
The issue arrises when those with a monopoly on violence abuse their powers to do whatever they want, or to enforce their selfish will on others. It’s very difficult to avoid that situation. Lots of oversight and repercussions are required, but that is basically never implemented. This is probably the main issue with police today. Near total immunity to do anything, including murder.
Police also inherently enforce the status quo and protect the elite. They enforce the current laws/state of things, as is their job, so they are always there to fight against change and progress (and regression). The elites typically define those laws and control the paychecks/priorities of the police, so the police fight for the elites. That is generally not good. An ideal society can mitigate this by reducing the powers of the police. Things like empowering social workers to respond to mental health crises or check-ups. Or limiting the polices’ capabilities for violence (guns, military vehicles, etc…) and delegating that to specialized task forces that only respond when the circumstances call for it. Adjust the violence level of the response to the situation at hand and come with a goal of de-escalation.
So generally, people aren’t calling for no police, they are calling for less militarized, less violent, and less immune police. Also, better trained police. A 6 week training course full of highschool dropouts should not be the pipeline for the police force. Bonus points of the police are actually active members of their communities.
Lastly, if police are just there to look busy and get paid, they tend to go after easy low-hanging fruit that doesn’t benefit society. Filling jails with weed smokers while refusing to purse any crimes that require a modicum of investigation helps no one.
ACAB is very accurate because the job description of today’s police is to be evil. However, that doesn’t need to be the case.
And now, lots of web searches return results of AI SEO slop chock full of incorrect information, which then fules subsequent training sets and LLM web searches and creates a negative feedback loop that could destroy the internet.