Bumping this because I'd like to get John Dule, lfromnj, or another yellow avatar's take.
Probably should be implicitly allowed by default but not sure why it couldn’t be included in a contract that disallows cameras .
In my case, there was no contractual rule against security systems. But that doesn't stop landlords from harassing you or making your life harder because you did something they don't like, which in this case would be protecting yourself from bad actors when the landlord/s failed in what ought to be their responsibility, for all circumstances. The consequence of that should at least be having the landlord forfeit some of their protections in eviction cases when they fail to protect their tenants, especially in high-crime areas.
(And that could include
not evicting tenants who are using their property as drug dens.)