More surveillance doesnt mean more safety. The US's murder resolution rate is 50% despite more surveillance than most countries. Even New York City, a place with an ungodly number of city controlled cameras and even more private cameras STILL has a murder resolution rate of around 50% as well.
And the resolution means a person is arrested and charged. It does not mean convicted. I don't know how often charges are dropped due to changes or acquittals or having a conviction overturned later due to any number of factors. All this means the percentage of solved murders is probably even less.