Doesn’t public_transport=platform already describe that it’s a public transport platform? It feels redundant to specify that it’s a platform twice using highway=platform (eg for a bus platform). If one wants to include the specificity that, for example, the platform is solely used for busses, then why not just platform=bus or some other tag that specifies use with busses? That would also potentially allow one to specify multiple types of public transport uses for the same platform without needing a new key like railway=platform + highway=platform etc.
To me it feels like tagging for the renderer as railway=platform and highway=platform appear to be rendered by carto, but public_transport=platformdoes not.
PTv2 has gained more and more momentum and acceptance in the last years. It is said to be complicated (not really, I’d say as a PTv2 addictive). Yes, tagging according PTv2 requires more effort, but there is good support in JOSM and the editor Relatify focuses only on PTv2.
However, this PTv2 did not make it into all data consumer SW, especially those with no focus on public transport at all, including ‘Carto’. So, some backward compatibility has been defined with the pre-PTV2 tagging schemes: highway=platform, railway=platform, highway=bus_stop, amenity=bus_station, … just to name a few.
