I guess for a long time UK banks saw ATMs as cost positive “automation” that might mean the reduction of wage costs and even branches. I remember when I could only use my own bank’s ATM or those of a partner alliance - and those alliances seemed to be based on favourable distribution. I guess at the heart of it was equitable cost sharing in the infrastructure.
I’d be interested to know how Link membership works. I assume some banks pay in to it and others receive revenue from it depending on how manny ATMs they provide to the network.
If you are a bank without any infrastructure, I guess that could only ever be a cost (which you’d offset against not having any retail premises costs).