Then everyone is happy?
Wrong
Married people with kids will be unhappy
Those in a relationship and want to work together will be unhappy.
Show does being married and having kids give you greater rights choosing your roster? Reminds me of the Swiss (the old one) girl working in catering I met in the mid 90's. She had worked the last 4 Christmases. Why? Because she wasn't married. Seems only fair, right?
The happy medium of everyone being able to choose rosters regularly (but not all the time) that KLM cabin crew employs seems to keep everyone I know there happy.
And at the very least you can look your colleagues in the eye and not resent their better deal which they did nothing special for to earn.