Disclaimer: I work in a bank and have worked closely with the customer support team.
Here's the thing: retail banking margin is actually quite low and customer support is expensive.
If you are someone who routinely calls your bank then your long-term value (LTV) is going to take a huge hit, so, of course banks want to keep everything as "low-touch" as possible.
A small anecdote: there were plenty of elderly people who were calling customer support every day to ask for their balance, because they did not trust the digital app. At some point, their calls started being routed to some chat-bot.
Customer support is also "embarrassingly outsource-able". The first layer of contact is usually done by someone who does not, in fact, work for "The Bank". They are actually employed by some huge contact center company who happens to have access to the bank's Salesforce CRM, and are instructed on how to solve most of complaints. It's only when they are faced with a very specific issue, that the ticket is then escalated to the in-bank operations team.
IIRC, we actually divide tickets in four categories: "L1, L2, L3 and L4". L1 and L2 are done by outsourced teams, L3 is usually the bank's operations squad, and L4 is the tech team with read-access to the database.