I just walked the trail on sunday and put about 5 miles in. There were a lot of folks out but a few places we were alone and a darn camera would do nothing for us.
The only reason for cameras are to make it easier for the police to fill out their incident reports. Actually, that is the real reason for the police in the first place, to arrest the BG after the crime and bring him into the justice system. It's not about crime prevention, it's about a legal reaction to the crime after it's gone down. If the public understood this, they might be more prepared.
We all know the cameras will not be monitored. The city has trouble staffing 911. My neighbor had a fire and was on hold @ 911 for over 20 minutes. She called the Pappa John's Pizza across the street form our local fire house and they went over and told the fire department. Again, YOU are responsible for your own safety.
Why this doesn't, philosophically, fall under the principle of pre-emption is beyond me. We either need to have uniform state standards, or none at all. This patchwork business is nonsense and does nothing more than create a legal minefield for otherwise responsible, law-abiding folks.