My favorite was the following:

- I still have a mortgage on a property but don't live there so the mortgage bill gets sent to a different address (b/c rental property)

- Company A originated the mortgage and sells it to Company B

- Company B completely ignores the mailing address and starts sending bills to the original property address

- only through blind luck did I realize that the mortgage bill was being unpaid

This seems like basic, basic bookkeeping but I guess it's also a reminder that "reality has more detail than people realize" and that there are plenty of opportunities for improving systems.

One of those myths too many programmers believe: All street addresses can accept US mail. Not necessarily the issue in this comment, but when somebody gives you both a shipping address and a mailing address and you send mail to the shipping address, the fault is yours if it doesn't arrive.

[delayed]