Re: Xerox photcopiers
Many years ago I was the IT specialist in a west London prep school (teacher, problem solver you name it - if it had a button I had to fix it).
All the classrooms had an inkjet printer and im my lab (?) I had a networked laserwriter.
When a teacher wanted to print multiples they sent it down and the printer would spring into life and do its stuff.
Except that now and again I would get a teacher coming down to collect something that hadn't come out, then another and possibly another.
Checking the printer queue would show a bunch of jobs queued up with an error message.
Turned out that a kid (and sometimes a teacher) somewhere in the school was attempting to print to American letter paper.
The printer only had an A4 tray.
It was still happening after I left. Some people never learn.