Relatedly, does a landlord have the right to know when you are in your home? Because that's a side effect of this (which could already be possible by monitoring things like electrical usage). Asking in both legal and ethical senses (which I expect are different).
The article mentions this is to replace a "key-fob". "Key-fob" implies some kind of RF read of the fob, and a potential computer behind the scenes checking if fob serial X is authorized entry at this time.
So the landlord likely already knows which fob's have entered the building at any given time. Presuming that most of the fobs are with their rightful owners, then the landlord knows mostly who is in the building at any given time.
The fob is not read on exit, so no. You can make inferences from frequency of entry, but you can't tell the difference between someone who is away all weekend vs. holed up in their apartment all weekend.
Keeping your name on the lease and then subleasing it under the table is one of the classic scams when rent control is involved. I can understand where the landlord would want to know who is actually using it.
This is a problem everywhere in the world, not just with rent controlled apartments. (Of course, those are a lot more lucrative.)
However, I'd wager courts would side with tenants that their right to privacy and ability to distribute a key are more important than the landlord's ability to fight subleasing this way.
Nothing to prevent owner of a building (landlord or other person/entity) from installing a camera and taking a picture
of everyone entering the building (outside the door). [1] Inside (legally) maybe the same no expectation or privacy in the lobby of a public building.
The end result of the landlord knowing when you are in your home does not change that.
[1] Same principle that allows you to photograph the police out in public or really anyone else.
If you have a camera that has any publicly available (not just public, also private-but-unfenced) place in it's FoV, you must register with your local data protection office and fullfill all the requirements (you must prove, how you use, make available, securely store and dispose any recordings).
If you don't have any publicly available space in your FoV, you must have a written permission from all the co-owners (e.g. in an apartment house).
So basically it is only easy if you are sole owner of the property and only you (and your family) are using it. Anywhere with a shared space, it is an issue. For a landlord, that would get no-go quickly.
I didn't investigate this further beyond my use-case (many co-owners, asking them to agree to anything is like cat herding). Given the protection the renters are getting, I wouldn't be surprised if such a permission would be difficult to get, and the common areas would be considered publicly available.
Relatedly, does a landlord have the right to know when you are in your home? Because that's a side effect of this (which could already be possible by monitoring things like electrical usage). Asking in both legal and ethical senses (which I expect are different).