An absolutely essential part of police work is to de-escalate situations. If someone is acting erratically and pose a potential danger they're supposed to be trained to calm them down, control the situation, and get it under control with minimal use of force. In America the work of the police is, to be fair, made harder by the fact that firearms are everywhere - situations can escalate very quickly.
However, if what starts as a pregnant lady shoplifting ends with you shooting her dead, chances are you did not do a very good job de-escalating the situation. Rather on the contrary - you escalated it a whole fucking lot.
This has nothing to do with any functional notion of police work. This is just state sponsored terror.