Earlier quoted context omitted.
It's a very easy trap to fall into if you're living check to check and make even the slightest mistake. In each such story online, I've heard a claim that they specifically have algorithms to maximize the penalty fees on these mistakes. Its another instance of a practice that disproportionately affects the poor. Unless you're living paycheque to paycheque, you would never even bother looking into such niggling detail…
I've heard it mentioned as 'largest payment first', with the stated argument that it's most likely to be a loan or some other important payment, but has the practical effect of triggering charges on way more items. It's For Your Benefit, citizen. (Also, the cash advance interest differential for credit-cards, which is higher, and only paid off after all other charges are covered, rather than any sort of temporal orde…
FWIW, in Canada credit card issuers are required to apply payments to whichever balances you're paying the highest interest rate on -- it's not even temporally ordered.