Neighbours live in a small new build style 2 bed house. Ground floor is effectively all open plan. They have 4 children (mix of boys and girls) - youngest around 5, eldest started secondary school last year so 12, coming up for 13 I guess. All 4 children share a room which personally I don't think is appropriate given the age of the eldest girl who either is or will shortly be going through puberty. They own rather than rent, we're in an expensive area so their house would be worth 350-400k.
More seriously, they leave all their children to play outside all day unsupervised, and have done for years. We're on a busy road (main road out of an estate) which is also a bus route. The youngest child in particular has no road sense and I have seen several near misses where he hasn't looked before running across the road, although none of them are particularly traffic aware. I've had all of them running across my drive while I'm reversing, or just standing on the pavement (my car is quite high up, and it's quite easy for them to end up in my blind spot) and they do this to other neighbours too. They also ride their bikes and electric scooters down the middle of the road again not properly watching for traffic.
I understand children need to play etc however as parents I feel we have a duty to make sure our children can do so safely before allowing them out unsupervised especially on a road where there is a fair amount of passing traffic. As to how I know they are unsupervised, you can't see into the street easily from our houses due to the road layout; occasionally (usually after a near miss) one parent will stand outside in the front garden for an hour or two 'watching' but they normally get bored of that after a day or so and go back inside leaving children to their own devices.
I think there is an issue here - so YANBU - yes, do something or YABU (beak out).