My three year old will happily run around the block, far past the point that you can see him, obliging you to give chase, but he is very careful not to run into

My three year old will happily run around the block, far past the point that you can see him, obliging you to give chase, but he is very careful not to run into the street, if he wants to cross a street he stops and holds out his hand. We also taught him to stop and look for cars before crossing a driveway, which he usually does. I would feel completely confident letting him walk down the block with his sister, in fact I do frequently, since I don't like to walk fast. That said, I definitely have met some three year olds that would run directly into oncoming traffic without restraint, so I think this depends a lot on the specific kid.