The key thing isn't that the banks (and governments, and enterprise software vendors, and ...) don't provide an alternative to the app as authentication factor. It's why they don't do this.

It's not about security. It's about them wanting people to use the apps. Forcing everyone to use an app streamlines the vendors' operations, reduces the state space of possible user interactions down to small number of flows they control directly, and also provides them a direct channel (communications or upsell, where applicable) to the user.

This is not a fluke or a conspiracy of small number of influential players. It's an emergent alignment of incentives across pretty much the whole supply side of digital aspect of human civilization (not "just" the market, because it's also happening in political and social spheres).