Re-consider rendering of amenity=car_sharing

[imagico]

In #1901 we removed rendering of amenity=car_sharing (https://wiki.openstreetmap.org/wiki/Tag:amenity%3Dcar_sharing) based on discussion in #1891.

I think it might be worth to re-consider that decision. Our understanding of the role of this style as well as the role of OpenStreetMap has developed since then quite a bit. As has the practical handling of car sharing in different parts of the world.

Back then the main argument was the limited usefulness of the information to the map users because users of car sharing would be using the proprietary apps of the operator. This is questionable from today's perspective because (a) OpenStreetMap is not unlikely to be a data source in specific car sharing apps, (b) car sharing users are likely not exclusively using proprietary tools of a single operator - but also might make use of more generic navigation tools for intermodal transportation or simply general purpose maps and navigation tools - like OSM-Carto and (c) car sharing stations are also a target for non-users of car sharing services - for example to meet someone who is using car sharing.

Apart from that the world is diverse and not everywhere operators of such services will maintain their own proprietary GIS databases with location information and their own proprietary apps (and even if they did - those might be worse in quality than OSM).

This does not mean i suggest we simply add this back. But we should IMO revisit the subject and newly evaluate the possibility of rendering amenity=car_sharing. Problems i see:

• It needs to be evaluated if the tag is used consistently in different parts of the world. In particular critical is the delineation towards amenity=car_rental (https://wiki.openstreetmap.org/wiki/Tag:amenity%3Dcar_rental) and amenity=car_pooling (https://wiki.openstreetmap.org/wiki/Tag:amenity%3Dcar_pooling).
• For practical usefulness it would be essential to display the name of the network/club the car sharing station belongs to. There seems to be competing use of the tags operator, brand and network for that. This is likely to be a major obstacle, in particular if we want to avoid a disaster like Labeling of amenity=parcel_locker incompatible with the goal of constructive mapper feedback #4629.