I certainly would hate to be watched all the time in my job, I don't see why officers should be.
It seems to me that a compromise can be reached.
Probably the rules already exist about reporting the headquarters when they are starting a police action, you just have to add the requirement to start the camera.
Are you provided a firearm, taser, mace, and baton as part of your job? Is your job funded by taxpayer money? Are you expected to be able to deal with stressful situations that could endanger your life daily?
If you answered yes to any of the above questions, I think it's an apple to oranges comparison.
It seems to me that a compromise can be reached.
Probably the rules already exist about reporting the headquarters when they are starting a police action, you just have to add the requirement to start the camera.