Share and share alike...

Yesterday was my little one's open house at preschool. My husband and I watched in apprehension as our child managed to grab several toys away from other children. We worried together that he would be ostracized for his lack of "sharing" skills. I vowed to rehearse these situations at home before THE BIG DAY.
But honestly, kids just don't like to share. Frankly, I realized, neither do grown ups. What would happen if you and your neighbors had one Mercedes to share among you. Can you imagine calmly and happily arranging a weekly schedule where you each got to drive it for a few hours? I mean, isn't this why we work? So that we don't have to share, but rather we buy our own "toys" so we can have them as our own? Our own car, our own house, our own iPod, plasma TV, DVDs, Playstation, what have you.
So is the problem that kids struggle with sharing? or that we expect them to do what we don't?