I am a child care provider and here's my take on this...
When you take off work and leave your child in day care so you can go to the beach or shopping or clean the house, what do you think is going through your child's head when they come home to see mom's new purchases, suntanned face or spotless house?
Do you think the kids don't notice that you spent the day hanging out having fun without them? Do you think they don't pick up on the fact that you'd rather not have them around? As a day care provider, I can tell you for a fact that even though the child has spent their day just like any other day, even though they have followed their daily routine without missing a beat, when they realize that you had an opportunity to spend time with them and didn't, they start acting out. They whine more and they cry more and in general misbehave more.
I once had a 15 month old girl whose mother was often home at least part of the day. When Mom was home or had been home the day before, more often than not, the little girl would refuse to take her coat off and stared out the window. I could get her involved in an activity and she'd be fine for a time, but would eventually wander back to the window. Most days she was fine, but when she had reason to believe Mom was home (and she was usually right) it was awful to watch this sad little girl.
It was children like her that lead me to include a clause in my contract that parents weren't allowed to do that to children in my care. I've lost some clients over it, but I don't care, because I find I get along much better with those parent who are left.