That stop may have been installed in the rental intentionally so that the owner or management can be called for service to deter residents from tampering with the fixtures or trying their own repairs. I did a valve change out in some rentals a few years ago for just that purpose. One of the tenants became frustrated waiting for service on a dripping faucet, turned the stop valve and somehow snapped it (probably used channel locks) and flooded several apartments.
It's easy to see how the intention of making them tamper proof could back fire on the owner in that situation.