Many people say ACAB for this specific reason - cops work for moneyed interests. To be a cop is to defend the wealthy and corporate, axiomatically. Plenty of cops are nice people, but they're working for a system that fundamentally is bad.
How nice can you really be if you sign up for, and continue to work within, such a awful institution?
If you want to say ACAB go right ahead - there's certainly truth in that. But there is also a truth in seeing that many cops got into it because they wanted to help people, and you're going to have to work with that if you ever want to fix the system.
Your point has some merit, but there's a big difference between being an engineer working with systems that can be misused and waking up every morning ready to crack people's skulls (especially since those people are usually impoverished, gender & sexual minorities, marginalized in some other way, etc) or outright murder them.
Yes, both people contribute to systemic violence in a way, but I would argue that there is a vast gulf between participating in society (which is mandatory) and being at the tip of the spear of violent repression.
Imagine having coworkers who routinely committed murder and received paid vacations for it.
That's how it was done prior to the 1800s.
Retain a small number of cops to deal with serious crimes (homicides, etc) and disarm them except in emergencies.
We also need to tackle criminal justice reform - ensure we have sufficient public defenders, ensure people have speedy access to trials, don't lock everyone in jail while awaiting trial, don't pressure people to plead guilty to crimes they didn't commit just so they can keep out of jail. Reprioritize minor offenses - who cares if someone has pot, why are we spending any time on it?