Furthermore, this 2021 European Court of Auditors special report pushed for the same [1].
A Supercharger station gives access to private users with an authorisation or a subscription so it's considered accessible to the public. All charging stations accessible to the public should to allow multistandard recharging.
[0] https://eur-lex.europa.eu/legal-content/EN/TXT/PDF/?uri=CELE...
[1] https://www.eca.europa.eu/Lists/ECADocuments/SR21_05/SR_Elec...