The web site often requires an app for authentication. Some (not all) banks offer alternatives, which often come at a cost (either financial or time) that would, once you add all of the costs up, be catastrophic for the majority of people, because it's never one thing that is affected with these major gatekeepers.

They generally use SMS authentication. I have yet to see one that has a hard requirement for an app, let alone one that actually requires a Google account.

Regardless: The fact that a specific tool is the easiest way to do something doesn't grant you a "right" to that specific tool. For example, you have a right to seek transportation; you don't have a right to a specific 2025 Toyota Camry provided by a private company.