And access to a solicitor & legal advice? How would that be maintained on the street?
Do you get those if you've not been arrested?
There's a big distinction between questioning people and arresting them. Sure, you could have a lawyer present every time you interact with the police, but you might find that the only benefit is to your lawyer. As I understand it, if you are not arrested, you are under no obligation to tell the police anything anyway.
On the whole, I think BWCs are a very good thing.
They keep the police honest (they have been shown to reduce the number of complaints of heavy-handedness against the police), and they are also useful in gathering evidence, especially when a crime is in commission.
After all, video evidence of a crime being committed stands up much better in court than first-person testimony from a police officer, and isn't subject to the human flaws of imperfect recall. This can also be valuable in the sadly all-too-common domestic violence cases. Where an officer attends a report of a DV attack (for instance a man beating his partner), the video evidence can show the injuries a victim may have received, without later having to rely on a combination of doctor's reports and dragging the victim through court as a witness, a process criminologists refer to as 'revictimisation'.