Well, for whatever reason, some people like to be difficult! I am sure there are plenty of stories on BBC News involving unions etc. If you ever get really bored, please feel free to come and visit a few crewrooms and you may understand better
I've told my employer before I can't work on limited occasions [for example the phonecall last Friday of "please can you come in and work and nightstop on your days off".....] and we have to be very flexible - the way my working week has changed this week is a perfect example of that
, going to work in Edinburgh for a month at 10 days notice another - but anything that requires planning / agreement in advance for whatever reason, seems to prove difficult! Don't ask me why, as I said, I fail to understand