The largest unknown is what even IS simple?

Here's a story from more than 25 years ago. A user couldn't print a document and calls local support. After they try several things remotely to no avail, the support person comes to the user's desk. Turns out there was a popup window asking the user to put paper in the printer and press ok to retry. How they missed this obvious thing (it was even a MODAL window) is a mystery.