Here's a fun one:
Bank fraud protection services, and the way they work.
If you try to make a large purchase with your card, & the bank denies you, at the register, because they suspect your credit card has been stolen. Not only do they decline that purchase, they freeze your card until you've called them and jumped through all their hoops, verifying your attempted purchase amount, the amount of your last deposit, etc. and even though they say you're clear after that, it can go on for days where you'll find yourself getting declined, calling the bank, verifying yourself, etc., etc.
All this with a so-called $3,000 per day spending limit, and $1,000 overdraft protection!
This is embarrassing, frustrating, & depending on what you're trying to buy, infuriating.
Last time this happened to me, I was at the pharmacy. My insurance has me pay 100% due upfront for prescriptions, so my transactions can be large. With more than enough money in the bank to cover the purchase, and no pending transactions, I got declined because of this stupidity.
I'm not really going to suffer if I have to wait until the bank opens to get my prescriptions, but OMFG someone else might! What if I were diabetic or something, or very elderly, and it was Saturday afternoon? One month the transaction goes through, the next month it doesn't...that's crazy!
Annoying to me, but for others, it could be life-threatening. Sadly, I think someone's going to have to die & banks are going to have to get sued before this changes.