Just checked to re-confirm: Wells Fargo passwords are case insensitive as well. This doesn't confirm that they store passwords in plaintext, as you said they may just convert to uppercase before hashing, but it is bad practice either way.

There is a lot more possible entropy if QwErTy and QWERTY are distinct. However, there seems to be issues in the entire financial sector with inability to upgrade certain systems due to massive amounts of legacy code. That being said, my local credit union's system distinguishes case for passwords; and they were unable to give a family member their password (they had to issue a reset) which at least leads me to believe they are hashing passwords instead of storing in plaintext.