Well, 16 isn't so bad. Here, in France, BNP accounts must have exactly six digit passwords. They're also incompatible with password managers: you have to click the number on a visual number pad.
I've had business and personal accounts with SG, La Banque Postale, BoursoBank and CIC and they all worked with those 6-character "visual number pad" logins.
I doubt it. N26, which is granted a "new bank", doesn't have that, even though it now has an actual French subsidiary, complete with French account numbers. My password with them is way above 6 characters, and contains numbers, letters and symbols. The login page has a regular password field.
I think the others are just copycats. Someone must have come up with this first, and the others figured "yeah, that looks so secure, let's do that, too". If I had a penny for every CSO who justified some stupid "security" idea with "everybody does it, why shouldn't we?" I'd be so rich I wouldn't care about this crap anymore.
To be honest, I'm neither a web dev/designer nor do I have bad sight, so I admit I don't really know how accessibility works. I expect this to be compatible with screen readers somehow, they even say they take this seriously. But from a quick glance at the Accessibility tab in Firefox, I see many complaints about "interactive elements must be labeled".
Obviously, if the computer reads aloud the password as you type it, it's an absolute win for security, and I'm sure some PMs somewhere are quite content with a job well done.
