Where are they going to put the button to turn it off when they need to convince a stubborn citizen?

Yeah, usually the bodyworn camera falls off the shirt at a critical time. Maybe a lot of drugs and guns will start to be discovered inside and under police cars.

In seriousness, having more surveillance on police action is probably good, but this seems to also come with indiscriminate surveillance on regular people as well, and that's going to have a lot of negative side effects.

I think the need for surveillance of police is so high that incidental surveillance of others may well be worth it

The city is in a budget season right now and people are being arrested for things that normally would not be cognizable as crime.

I agree that we should be willing to pay some nontrivial price to have more eyes on policing, but this camera installation push (both here and subway) is a big concern because we don't know how it will impact arrests and prosecution yet.