My parents have five siblings each, but I only have a sister. I know it sounds bad, but I wonder if having less kids makes you worry more about keeping them safe. Perhaps my parents just sort of continued with how they grew up, but limited me and my sister a bit more, and I'm limiting my kids even more? Or it could have to do with media, where my grandparents wouldn't get news about abductions in the US and walk around worrying about that in their small Scandinavian village. Or it could be a time thing, where my grandparents just didn't have time to supervise the kids full time, so the older siblings had to guard the younger. Now, me and my wife will take turns to bring them to the park, and if we don't have time, the kids (at least the 5-year old) will have to stay indoors.
I try to give my kids more freedom than I'm comfortable with, but I just know that if something happens, people around me will think I'm a neglectful parent if I let my 9-year old stay out until 8 PM on her own. I want to give her the opportunity to explore the neighborhood on her own, and learn how to navigate the world. I mostly worry about cars hitting her, because I've almost been run over a couple of times where cars should have stopped, but she has to learn to look out for herself.