I have been using Wells Fargo for almost thirty years and while I don’t know if it’s still the case, as recent as four years ago their passwords were case insensitive. I’ll take a little sane fintech in my banking please.
If your answer is: because 62^8 (^12, ^16) is much bigger than 36^8 (^12, ^16) then I assume you don't actually know how people crack passwords, which isn't brute-force.
If your system is capable of being brute-forced, you already failed, because there's no reason to give someone enough guesses that a brute-force approach succeeds.