Who will be the nasty grownups

Yesterday we were at the local park. We'd just stopped in on a whim, so my son didn't have a bunch of toys for the sandbox. He promptly ran up and grabbed something. I, in my mom-role, followed up and told him that it didn't belong to him. The mom said "oh, that's ok." And so it went, the rhythm of the park. Impetuous child (to put a nice word on it) grabs, owner child notices, often protests, and mom says "if we bring it to the park, we share," or at least tries to get child to share. Until we get to "Bobby." Bobby shows, dumps toys out, Simon runs over and grabs, I say "that's his, please put it down," and Bobby's mommy says "Don't you want to share?" Bobby (of course) says "NO." Mommy says "are you sure?" and Bobby says "I don't have to." Mommy kind of laughs and says "well, he doesn't have to." I, of course, had already gotten Simon out of there, but .... whooooo-eeeee! Mommy's raising one lovely little single child there! Ick. Later on, Simon goes back (he's nothing if not tenacious) and grabs something again. No, I'm not a bad mom, he's just a whirling dervish. I say "put it down, that's not yours." Simon, who can now speak, says "Why won't you share with me?" Bobby grabs the toy and Simon yells "NO!" Bobby's mommy is there, making "Oh now Bobby" sounds. So I sit down, right in front of her child and say "Simon, Bobby doesn't want to share. That means that you cannot touch or play with any of his toys. Why don't you go to the other end of the sandbox?" Simon says "I'm not going to play HERE!" and dashes off. Now can any of you who are mothers believe this? Wow. People choosing to eschew your child's space because he's so unpleasant? By the way, Bobby had approximately twelve toys in front of him. I think that, given the town and socioeconomic levels, let me see. Bobby will go to a very expensive school. He will always get whatever he wants. He will probably be a good skier, maybe learn to sail, and he will never, ever, see a reason for sharing. In short, he sounds utterly terrible. Like a total jerk for life. Great job, mommy. The other children, on the other hand, will learn social skills, will learn to share their toys in an increasingly pressed world, and might actually go out and do something socially responsible with their lives. Like raise their children to be friendly and share their toys!