One thing to consider is that Many people simply do not have the time, energy, and/or equipment to cook food from raw ingredients. These factors are common in poorer households where people are working multiple jobs, etc.
I literally just puts the thighs in the air fryer (I have a cheapy one from Tesco) for 30 minutes. The steamer I have was £15 in Sainsburys (it was on offer).
Most kitchen equipment except for the white goods is dirt cheap and even the really cheap stuff can last for years. Most meals take me 30-40 minutes to cook maximum.
That isn't 30-40 minutes me standing in the kitchen cooking. That is how long it takes to cook in the air fryer (the thighs take about 30-35 minutes). I literally have a timer telling me when to put on the veg and the potatoes. I think prep time is max 10 minutes and then 10 minutes to wash up.
In any-event. It is objectively more expensive to buy junk food, that includes the cheaper junk. Once I cut out the trips to the takeaway and the deli, I was surprised at how much more money I had per month.
That's certainly an improvement, but still involves me planning to eat in half an hour instead of just snacking right now. But I shouldn't be presenting myself as representative of any demographic except maybe bedroom coders. I tend to agree that junk and expense correlate. I don't eat junk, I eat random crap, it's very different.
* Bananas, a fine inexpensive convenient snack.
* Buy bread and sandwich fillers, add sliced tomato, not awful for you and not time consuming.
* Tea is cheap, I like tea.
* Cereal can be good if you can find one that hits the sweet spot between a bowl of chocolate and a bowl of chaff. Some sort of granola maybe.