"Sam Hopkins" sez:
If you are a concerned parent, this may be a good time to be a meddlesome
neighbor. Assume the neighbor wants to know about dangerous conditions, and
offer to help find a solution. If a law is being violated and the neighbor
won't cooperate, contact the appropriate authorities.

I agree with everything you wrote but this last paragraph. If you are a
concerned parent because you're afraid your kids may get into trouble on
your neighbor's property, give them up for adoption; you're clearly an
unfit parent.

Better still, train your kids to behave better. Watch over them. If you
nag your neighbor to do your damned job, you will wind up much less happy
than if you just do it yourself.

Now, that said... if you are a concerned NEIGHBOR (i.e. not limited to
incompetent parents) with no children or well-behaved children who would
never get into such messes, but you've seen other kids in the neighborhood
with all the self-control of excited spaniel puppies not far from the
Pandora Box, then you might consider saying something like this...

"Joe, How ya doing? Hey, ya know those mutant rugrats on the scooters
that have been gettin' into everything lately? I saw some of the little
vermin playing around your (pond/shed/whiskey still) and thought to myself,
'There's a disaster waiting to happen.' I've tried talking to their
parents, but they're those yuppie types with the Volvos, ya know, and can't
hear nothing unless it's over a cell phone, so I was thinking... maybe a
hasp-and-lock or a fence? If you're up for it, I'll help next weekend;
I've been wanting to try my new cordless drill..."

Much better than some idiot new-age parent nagging their hapless neighbor.