I dunno - I have a seven year old whom I try to allow to be as feral as possible. We let him go alone to the neighborhood park, which requires seven small residential street crossings. But I would hesitate also about a multi-lane stroad if there wasn't a lot of pedestrian traffic. Kids are small and cars have gotten huge and drivers are very distracted, especially post-pandemic.
(We're in the US, and I draw the line at letting him cross ordinary 25mph residential streets but not the "25mph" artery road on which many of the drivers go 40mph. It's only one lane in each direction but there are no lights or crossings and the effective speed is quite high.)
