I see private charging stations at objects like chalets which are a feature of the amenity and think that it would be “wrong” to map them as node on the map because they can only be used by tenants so I propose using charging_station=yes to indicate that an amenity offers this to it’s “customers”.
Taginfo already indicates ~85 instances of this tag.
From first glance, it might also make sense when one knows that an amenity/building/etc. has a charging point but one can’t necessarily accurately map it’s location (say, if satellite imagery doesn’t yet show it).
I wonder if charging_point=yes might therefore be more consistent?
Though I think the idea is that man_made=charge_point should always be located inside an amenity=charging_station so I’m not too sure! Perhaps charging_station=yes is more adaptable in case an amenity/building/etc has multiple chargers available.
As @chris66 says, we would need at least a distinction between bicycles and cars. On the other hand, bicycle charging should never be a problem in amenities like apartments or hotels. So, we might be able to restrict this tag to car charging stations.
But I highly recommend to not add any more details (socket, output, capacity) to this tag because it would make tagging way too complicated with yet another namespace prefix. This information should always be on a dedicated node, marked as access=private or access=customers.