Here's a funny example. I know two different people named Katie. I am assuming KH would approve of both as it's her name, too.
The first Katie is from a very wealthy family, lived in a huge mansion when she was growing up, went to all the best schools. At the age of 21 she died of a blood infection due to injecting heroin with a dirty needle.
The other Katie is from a working class family, lived in tiny flats growing up (different ones as her single mum was always behind on rent), wore second hand clothes, worked super hard to get through school and go to uni.
Katie Hopkins going by her self-proclaimed rules would've let her children play with both, but probably would've preferred the middle class Katie to the working class one, eventually. So her DD's, had they become best friends with MC Katie, would probably more likely had become exposed to illicit drug-taking than if they ran around with WC Katie.
I do think SW are referred to lower class families because sometimes the abuse or neglect isn't hidden as well. I know lots of incidences of abuse in higher class families, but there is more pressure to cover it up in order not to tarnish appearances.
By the way, the working class Katie is me. The middle class Katie was my childhood best friend. We met at nursery.