I don't work at a bank, but I do work in fintech, and this strikes me as excessively cynical. The reason banks are slow about this stuff is not necessarily because "it's cheaper" (though maybe it is), but because the complexity of any change is simply off the charts: money-related logic must work correctly, to a far higher standard than almost any tech company. It makes you conservative, in the same way that demanding 99.999% uptime is exponentially harder than demanding 99%, and makes moving quickly essentially impossible.
(Also, of course, they're probably working on COBOL stacks that were written in 1978.)
For a bank, pile on top of that mountains of (often conflicting) regulatory review, such that just about any change sounds the alarm for armies of nearby lawyers to swarm upon you and bury you in paper. All it takes 0.1% of annoyed users filing complaints that they can't access their accounts, and you might well be looking at a steep fine, a class-action lawsuit, or worse.
(Also, of course, they're probably working on COBOL stacks that were written in 1978.)
For a bank, pile on top of that mountains of (often conflicting) regulatory review, such that just about any change sounds the alarm for armies of nearby lawyers to swarm upon you and bury you in paper. All it takes 0.1% of annoyed users filing complaints that they can't access their accounts, and you might well be looking at a steep fine, a class-action lawsuit, or worse.