Rice beans and nuts - OK not interesting food, but super healthy and cheap. Am I missing something here?

Here in the UK, it's often reported that the poor cannot afford "healthy" food (it never states what healthy food is) and instead they eat unhealthy food - one can only assume they mean stuff like McDonalds?. This never made sense to me, you can buy rice, potatoes, tins of beans, pasta for far less than a burger or a curry. There are YouTube channels dedicated to cooking meals using super-cheap ingredients.

Occasionally I'll just eat a bowl of porridge (with milk) when I can't be bothered cooking. Not only is this extremely cheap but also healthy. You can dried fruits and nuts if you're feeling adventurous. Peanut butter also works.

This whole "poor people can't afford healthy food but can afford unhealthy" needs to stop.