There's a big correlation between being disabled and being poor. Disabled people as a class are more likely to find scratch cooking hard to do and less likely to be able to use money to compensate for that by buying meal prep kits or the healthier types of "ping" meals.
As an example: me, I'm autistic. Today's a really good day for me: I've had a shower and brushed my teeth and got dressed before sitting down to my desk to work, instead of being unwashed and in my dressing gown. I've not had breakfast yet because I didn't have the mental run time to deal with food preparation and also deal with mentally preparing for my first meeting. Brunch will be in a few minutes and will be a shaker of Huel. Dinner will be a shaker of Huel. Supper will be a shaker of Huel. Cooking is an utterly daunting task that I can manage perhaps twice per week, usually at the weekend. When I last heated a pizza, I forgot about it and it burned. This is normal for me.
I also have chronic tendonitis in my wrists. Some days, I cannot hold a knife strongly enough to cut veg even when I have the mental run-time to cook. I use frozen veg to work around this, which means owning a freezer, which meant an initial outlay that many people can't afford. I can't just push through the pain and cut veg anyway because then I can't move my fingers at all and I have to type in my job. A lot of my job involves spreadsheets and databases and you can't do that with dictation software.
There's also the mental load of remembering what goes out-of-date when. It's all very well saying "plan a week's menu and buy to the plan", but when I get home from an office day and don't have the mental run-time to cook, that day's ingredients are wasted.
As disabled people go, I am extraordinarily lucky because I have an above-average paid job that leverages my strengths and so I can afford Huel to cope with the fact I don't have the mental capacity to work and cook. If I couldn't afford Huel, I would be eating toast, pasta, crisps, canned soup: unhealthy high-carb fattening stuff that needs bugger-all effort. This is what unemployed and underemployed disabled people end up eating.
So it's not a case of "just go to the greengrocers and buy cheap veg and scratch cook" because some of us can't.