I’m sure costs is part of the equation but I’d imagine the control is far more important. Reselling legacy bank services means you’re limited to what they can do, which is usually not much. Most finance technology is heavily limited by what they can do… because of their partners, and that’s why they’re usually just nicer interfaces to the same old services. Hence banks like Monzo in the UK building their own infrastructure from the ground up too. The less you’re dependent on legacy technology, the more you can do.
