Although I agree that this criticism of Canadian banks is probably broadly true, note that the banks did manage to coordinate on Interac, a quite serviceable standard for sending money electronically between private parties.
I'm guessing the benefit to banks is lower fees or perhaps even monetization through transaction data sharing with Visa?
This of course breaks Interac features like Interac online.
Last time I opened a bank account and got a co-badged Interac card I immediately asked them if I could get an "Interac Only" card. At first they had no idea what I was talking about, but a few phone calls to head office later, and they were able to re-issue new debit cards without the Visa co-badge. Interac online works, and I feel better not sharing purchase data with Visa.