I'm talking about using a normal card or multi-currency card for digital only services (subscriptions) and store fronts tied to a specific region where a valid billing address & phone number (a local one) is required (must match the country too) upon entering card details via the App Store, PS Store, eShop or Steam won't accept US cards on a non-US account on these storefronts (like JP App Store refuses US bank cards).

This is the issue with going "cashless" as it's REGION LOCKED in this case, as they demand a billing address including a phone number alongside a new card that matches that country (meaning your home country's bank card is useless for a foreign Steam account, since refer via BIN: where the card is from rather than letting the transaction go through, it'll display an error when using a US card on a Japanese steam account).

The thing is that, why do physical retailers accept foreign cards for tourism but App Store, PS Store, eShop or Steam refuse to allow cards from tourists as these services use BIN as an identifier, basically them saying "tourists can't have another country's apple ID as a billing address & local card is required" only an expat or PR holder can really do this since they have a new card and live in the country (has billing address).

Travelers use multi-currency cards but remain stuck when it comes to App Store, PS Store, eShop or Steam as that is tied to where they are ACTUALLY from rather than the destination they're visiting. Even PayPal is region locked (only expats can register a foreign account as they live there), a PayPal account is tied to where YOU live as banking information has to be consistent with their residential status rather than visiting.