quality posts: 6
If there's a chance of physical harm or something, I would at least give the other parent a chance by letting them know what's going on. If they seem too preoccupied/disinterested/lazy/etc. to care or do anything, I'll speak up. If it's just kids hogging toys/playgrounds/whatever, I tell my kids to deal with it or do something else.
The whole notion that if some kid wants what another one has so the parent makes them share is bogus in my book. If you had it first, you can have it until you're done with it. The other kids can find something else to do or play with.
I have 6 kids between 1 & 14 years of age and have seen a lot of this kind of stuff over the years. It also seem like a lot of folks have migrated more to the extremes these days. Either way too overprotective, or don't know what their kids are doing 99% of the time. I try to keep things pretty centered with my kids. It's not super easy, but finding a good balance of choice & control seems to be best in the end.