Why do so many mothers whine about "me time"?

I don't feel that way. Ever since my daughter was born sure I was too busy to go get a manicure or take a decent nap but it didn't bother me because nothing is more fun that spending time with her. But I constantly hear moms say they need a break or a vacation or they'll go nuts. I couldn't handle being away from my daughter for more than a day and even that would be pushing it (when she goes into school I'll be so sad!).

Anyone else feel that way about their children? And I know some will probably say, "You only have one wait til you have two". Well I know plenty of moms who complain and only have one child.