Of the measures available to the justice system for deterrence, increasing the perceived certainty of arrest is possibly the most effective.
An arrest also prevents the same offender from committing more crimes. Since offending is highly concentrated among a relatively small number of repeat offenders, this isn't insignificant.
A camera does not prevent the first crime that it records. But a system that makes detection more likely can reduce later crime.
Of the measures available to the justice system for deterrence, increasing the perceived certainty of arrest is possibly the most effective.
An arrest also prevents the same offender from committing more crimes. Since offending is highly concentrated among a relatively small number of repeat offenders, this isn't insignificant.
A camera does not prevent the first crime that it records. But a system that makes detection more likely can reduce later crime.