Article was short on details, like ages and age-appropriate activities. When can I let my child roam his city neighborhood? That would be extremely helpful.
You need to move to a place where unsupervised outdoor play at young ages is encouraged. These places do in fact exist in the US.
The common reaction to this is that you can't just get up and move your family. We'll this is still a choice and we all set priorities on what is important.
Also, there is no utopia so the "best place to raise a family" in the US might have other negatives, you just need to prioritize.
We live in such a neighborhood and it has been excellent for kids. They can walk or bike to the park in less than a minute, there are multiple playgrounds and large fields to run around.
I went to school alone since I was 7. As far as I know in much of the US people would probably sue you if your kid went alone.
In my town there are certainly young kids (i.e. elementary school age) who walk or bike to school on their own. Sometimes there are parents walking with them, but I think they do it because they enjoy a walk with their child rather than any real concern for safety. There are crossing guards at walkways where kids will need to cross busier roads.
In other areas, schools are just too far away to walk, or there are other difficulties such as major roadways with a lot of traffic. Then kids ride a bus or parents take them.