A few thoughts to add to the mix.
The problem is that there are 300+ properties with car spaces, that is a real headache to manage effectively.
Any access device needs to be programmed in some way. This means that they should also be able to be disabled using the building’s access control system. If the system can’t disable devices then you are caught between a rock and hard place.
Technically only residents / occupiers should have parking / building access. Family members are a grey area, particularly if there is only one occupier. Again if extra access is provided, if it is abused then the access control system allows for the specific access to be turned off.
When is a casual visitor considered a resident – when they behave like one, such as checking the mail, putting the rubbish out etc. This is not behaviour of a casual visitor.
Cheers