Is it no longer safe there? Because in the states parents have been restricting kids a lot more severely just as crime in cities plummeted (mid 90s--present). So I imagine it's either perceptions about safety, or parents just being more careful.
It isn't no longer safe for kids to walk to school. What happened is that American internet arrived here, and it has political reasons to want everyone to think it is.
I walked to the gas station with my dog and two kids, and had a guy yell at me that my kids were going to get kidnapped while I went inside for 5 minutes to buy us some waters and snacks. The biggest hurdle for us letting our children be free range and able to do things on their own has definitely been paranoid parents and busybodies who watched Sound of Freedom and think that every girl is going to immediately get sex trafficked to Guatemalan drug lords (or whatever, I didn't watch the movie) if she leaves her parent's sight for a second.
As far as I can tell, American Internet mostly wants you to think that their own culture war is important and relevant universally, including for you. And that their own particular division of issues between their political poles is also somehow universal and important; and that you should get riled up about it.