The little one I have today was dropped off on daddy's day off... I fully expect to mind her as I am being paid to do so. Dad is off to a war museum! He is working this wkend. Some childcarers find this odd... that parents still need care for their child when they are off. I don't.
I don't think it's a case of not wanting to spend time with their lil one as they always ask me to mind her on their days off, but they are paying for my service and I expect her to come. They can do other errands etc. on their day off and spend quality time with her on the wkend.
It's also a case of watching the pennies... they HAVE to pay for the space, even if they are off, so get their monies worth... all my parents do this.
Re holiday notice, it is good manners (and should be contractual) that all parents give holiday notice, not only the minder.