You would think that if the kids are getting that badly burned, the mother should also be getting pretty toasty, but the little information in the stories I've seen really don't give enough information to tell.
Me, I had a couple of instances where I got severe sunburn when I was a kid - once I played in a wading pool too long, and there were a couple of other instances of bad sunburn where (some time later after healing a bit) skin would just peel off in large strips.
Was my mother neglectful? I wouldn't say so - but of course back then, parents let their kids do all kinds of things that would probably get them cuffed and put in the slammer nowdays. I'm sorry, but somewhere in the past 40 years or so we've gotten quite too much of "make everything ultra safe". (Thanks, lawyers and judges).