This seems to be more of bank-to-bank protocol than a bank-to-customer protocol.
I was developing these apis for one of the biggest banks in central/eastern Europe.
You’re right that they are not intended for bank to customer access directly. What they allow though is for third parties (other banks, mobile apps, services) to access these apis. It requires a licence though.
Point is that a lot of banks in Europe allow to add other bank‘s accounts to their app. Also aggregator apps exist.