I think what frustrates some of us is not the parents who occasionally take their day off to themselves, but the ones who constantly do it. Also, when it comes to say, Christmas holidays, when you have almost all your dc families taking days off and actually spending time with their kids versus the parents who will take the whole 2 weeks off and throw it in your face that they are off and don't even think of coming to pick up even a half hour earlier.
There is nothing wrong with taking the afternoon to do some shopping or get your nails done, if your paying for it. I have been a working mother as well, for years, when my kids were little....I totally get it. But I'll be damned if I spent every single one of my days off or holidays without spending some time with my children. Now that one of my boys is grown and moved out and the other is approaching his teens, I think back and realize how fast they grow up and how important it is to spend those younger years with them..