Say that you subdued a drug addict, who resisted arrest and was having a panic attack, according to the department prescribed method for that exact circumstance while waiting for an ambulance, and then say that the person died maybe because of a drug overdose, maybe because you used the subdual method incorrectly, and then say that the video was released, say that video incited national riots labeling your actions as murderous, and say that anyone who defended you had their entire life destroyed by cancel culture, and then say that a politically motivated state AG charged you with murder under a theory that is discredited in almost every other jurisdiction in the country (felony murder without a merger doctrine). That is an extreme example, but it could happen.

To avoid that kind of thing, a rational, honest police officer, who has no other marketable skills at age 37 and doesn't want to be tried in the court of public opinion circa 2020, might resist being filmed.