Paying for a premium cabin overcomes these problems.
I suspect that UA reckons that keeping employees happy is very valuable.
Generally 100% agree with this - you want it, pay for it. I had NRSA benefits as a kid, and was always taught that we were on best Sunday manners there. However, more and more, this doesn't seem to be the case.
Saw a post on FB this week, friend of a friend who's an AA FA, posts a pic in a ratty t-shirt "too many FAs scheduled so getting paid to sit in first class and not work today from CDG. Feel bad for the suckers who paid for economy - NOT!"