I used to live above a family of 4. Pretty much of the lower class (economically speaking), and the way I would hear those parents talking to their kids very nearly made me call DSS. There are so many factors that come into play though. The stress of never knowing where the money is going to come from not being the least of it, but I could never tolerate hearing those kids spoken to that way. It made me sad and mad.
People learn what they live with as children, and so it gets perpetuated from generation to generation.
My family background is working class, and my parents never used four-letter words around me when I was a child. And I got a good spanking from my mother when I was five or six years old and she caught me saying, "What the hell?"
The way I see some parents speak to their kids in public--yelling and screaming at them--and treating them--jerking them around by the arms--makes me sad.
Do I say anything? No. If the parents act that way toward their kids, how will they act toward a middle-aged stranger who says something?