British parents don't supervise their children. I lived as an expat in a 'little england' type of area where all the kids were basically feral, even 2 year olds were out by themselves constantly. It was a mostly safe, mostly white area, but nowhere is THAT safe.
We had a really little one throwing a ball at our house for weeks before summoning the parents by confiscating his ball. First they tried to send their older 8 year old to collect it (we were total strangers to them), and then they finally turned up and just made excuses as to why it was OK.
We had a pair of little girls at our house once for a couple hours because their parents (also total strangers to us) had gone shopping and locked them out.
And once we had to help a little girl find her house a few blocks away because she was lost. We wandered the whole area with her in hand trying to get a good description out of her, eventually found it, and we left her at her neighbors because her parents had also left and locked her out!
We were a child free flatshare, it's not like we had kids of our own for them to play with, and I just couldn't believe the level of parental incompetence on display.