American police have no obligation to protect, serve, or tell the truth. The police steal more money than all petty thieves every year.

Qualified immunity makes accountability a distant mirage.

The police operate exactly as they are allowed and encouraged, by the system they labor within, to behave.

Your words 'sloppy' and 'error' imply that a 'careful, correct' approach fixes these ills. History and experience shows us that this hypothetical good will not be produced until laws and incentives more broadly, change.