How do you suppose you increase accountability for police officers (or any other police reform) without public support? And how does increasing accountability give police officers the special skills that they increasingly need, for example, to for interacting with mentally unwell members of the community? "Figure out how to be a mental health professional or face jail time"? To use your "doctors" analogy, we also have a system that adequately trains doctors and filters out the unfit.
Just put the officers on the hook instead, reform done.
Doctors are on the hook for medical malpractice, works quite well and we still have doctors.