• Natural monopolies should be nationalised. Network effects tend to be a significant characteristic of natural monopolies (my opinion).
• Payment infrastructure is critical for national security. Just the way cash is.

This is why imo, there should be a nationalised institution competing against private institutions like these.

• the nationalised institution must be owned by the state.
• its operations however must be organized as a consumer coop, where cardholders of this payment network are member owners. This would prevent the top down bureaucracy, corruption and inefficiencies that plague state owned corps.