I think that it's a sad way for 2 little boys to live.
She may not be abusing them, it may not even be 'proper' neglect, but let's be honest, we all feel sorry for those children, as described by the op, don't we?
Not giving your kids enough attention is hard on them. And I feel sorry for them, if that is the case.
What can you do? Well, you can ask her if she's ok, tell her you're worried about her. She might be depressed, floundering..
Or you could tell her that her kids need a bit of interest from her, for their emotional wellbeing and she's letting them down.
Or you can report her.
Or you can do nothing.
Or you can provide that missing element yourself.
Depends what you think is best.
I know lots of people like this.
They have kids, they love them, they get stressed of course, but they're not bashing them.... but they don't involve themselves, iyswim. Kids fed, check. Kids dressed, check. Kids at school, check.
All the requirements, but not the other stuff.
And I think that (and I am thinking specifically of those people I know who are like this) this can be because they were never parented that way, they just don't know how to.