Hi @CroMagnon , “Welcome to Connect! If this is your first visit, you’ve come to the right place. This post will serve as a guide for everything you need to know about contributing content and engaging with the Local Guides community on Connect”. This is the first of the information that you will find in “Your guide to Connect” , the introductory Guide of the community. In there you will find all the necessary information to know how to better contribute in here.
Regarding your request, Banks are protected subjects in Google Maps, due to the risk of scam, so you have no, or just few possibility to have a single bank accepted in Google Maps.
Maps are usually added in Maps by the businesses itself, as they can easily manage all the branches, and they must be verified.
My tip for you is to talk with the director of the ones closest to you, to raise the issue, so that they can manage it with their Google Business Profile account.