Why wouldn't kids play on the street? What the hell. Should they never leave the boundaries of a building and its garden? I was running and biking all around local forests by myself when I was 10, and my children will do the same. They have a phone, so I am not worried they will hurt themselves without the ability to call me. And they keep posting nice photos to our Telegram group, so I even roughly know what's happening.

Yes, I'm implying that a 9 year old is mature enough to be online - if they have guidance and trust their parent. And yes, children are never too young to start trying out things - again, with guidance and a trusted parent, but that doesn't mean constant oversight. You teach children to look both ways before crossing a road, watch them do it for some time, and then you let them go to school by themselves. I don't understand how are they supposed to develop responsibility and self reliance if there's constantly someone watching.

Seems like your idea of responsible is my idea of sheltered.