Why are jeans not appropriate?
It's a bank. The part where they deal face to face with the public. Jeans don't offend me in settings where they're appropriate.
There are all sorts of situations where jeans aren't appropriate. I never wore them when doing my student teaching practicum, for example, or when I did my organ exams and recitals. I didn't wear them when doing the census or working for Elections Canada. I didn't wear them when doing front of house work for any of the theatre companies I was involved with (one of them had a strict dress code which meant having to show up in black slacks, white blouse, and put on a black vest (I skipped the tie and nobody complained). I did wear dresses when doing front of house in costume.
About the only time that I did wear jeans when others pitched a fit that they weren't appropriate was at the opening night party for the first musical I worked on (wine & cheese party for the patrons). I got scolded for not wearing a dress, and when I pointed out that my job in the play involved crawling around in the rafters and sitting in a hot lighting booth for half the night, plus climbing up and down ladders - and for which a dress would be a completely impractical thing to wear - they said, "You should have brought one with you and changed after the show."
Yeah, right. Change where? That was two years before we had a dedicated props room where I could have just closed the door for a couple of minutes' privacy. Otherwise, I'd have had to use the same dressing room as the female cast, and they wouldn't have been happy about that.
So I didn't change. At least it didn't offend one of the patrons, who as it turns out, was friends with my dad. It surprised the snooty crew heads that I'd know Somebody Important, but that's their problem (this was before I became a crew head myself - and I never tried to dictate what my assistants should wear).
If it had been practical to change for the party, I'd have done so. It wasn't, so I made the best of an awkward situation.
The bank teller didn't have this problem.