My DD never goes to school without breakfast, but I'd never judge anyone else on why their children don't unless I know the full story - and unless you live with these 'chaotic families' you don't.
There are too many reasons why people don't or can't provide breakfast - and I don't believe it's just because parents can't be arsed.
Don't get me wrong, I know it does happen, but I don't think it's the majority.
I'm sad to admit I never got fed properly, smelled often, was ostracised by my peers at school - all due to neglectful parenting, but it wasn't willful neglect. My mum had mental health issues, suffered domestic/emotional abuse, drank too much, smoked too much, ate too much... she just couldn't cope. She frittered any money she had on things we didn't need, but that she thought we would want or like to make up for her shortcomings, but she couldn't get the basics right.
Take a family in a similar situation today with additional pressures e.g. low income/benefits, high unemployment, social exclusion etc and add in a punitive sanctions regime, zero hours contracts, massive child care costs, bedroom tax and so on and so on and see how you go.
Not a religious person, but the phrase there but for the grace of God go I comes to mind.