It must depend on the neighborhood, or on the social class. As a middle-class frenchman living in the outskirts of NYC and accompanying my kids to plenty of bir

It must depend on the neighborhood, or on the social class. As a middle-class frenchman living in the outskirts of NYC and accompanying my kids to plenty of birthday parties or playdates my experiences are anything but "structured". If anything compared to France parties tend to happen more often at stores or specialized venues than at people's home, but schedules are pretty much the same: play, eat, and more play, with light parental/staff supervision.