In some (EU) countries, as a public officer/agent you can actually get prosecuted (civil or criminal proceedings per case), in cases of blatant or willful incompetence. (Think of the levels of gross wanton disregard/negligence.) (There is also the legal vehicle of insubordination.)

For instance, in Greece https://www.lawspot.gr/nomothesia/pk/arthro-259-poinikos-kod... (N.B. the bar of wilfulness in this section in the Greek criminal code is much lower than the corresponding notion of wilfulness in the U.S.)

The bar is high, of course, and yet people have historically managed to get prosecuted, lose their jobs, and go to prison.

I think the problem in the U.S. is, ironically, the power of police unions in a fragmented police force (city, territory, county, etc.) ecosystem, coupled with the lack of unified, express state and federal statutes to enforce a standard of care and competence.

Add to that that peace officer-specific state statutes (e.g., describing manslaughter while on duty) are written in such a way that, as a matter of law, it becomes a herculean task to tick all the boxes to successfully preserve a conviction on appeal. It is truly troubling. (I am hopeful, as this can be solved by the U.S. legislature, which I think we have a lot of reasons to demand to be done.)