I think people can survive on whatever is available, yes, but if you can eat lots of vegetables it helps with so many things from just feeling better to minimising long term risks.
What I think is a disgrace is that it's deemed acceptable for some sections of society to have to live off foodbank food which is not nutritious, it's been normalised by the government and some of the public.
I'm on a really low income and I spend a lot of time and energy in making sure we get at least 5-a-day. My budget for myself and two teenagers for all food, toiletries and cleaning products included, is £50 a week.
To get our 5 a day on our budget, I have to calculate the cost per weight of everything and walk to the supermarket most nights at around 8pm (yes, even after work), and get the yellow sticker fruit and veg and also other foods at about 75% off. I either use it up or I make sure to blanch and freeze it before it goes off. It's literally the only way we can get enough veg really, which is really sad in one of the richest countries with me working and with low rent.
I batch cook 4 recipes on one of my days off. I have like a whole day of cooking on one of my days off, I play podcasts and quite enjoy it. Take lunches in a thermos food flask. Never buy drinks out.
I usually say 2 veg at lunch, 2 veg at dinner, and one piece of fruit. Sometimes we end up getting more.
I think it's easier if you like most foods, as we do. DD is veggie and me and DS are not.
Also much better if you don't have a sweet tooth. I used to have a sweet tooth but somehow my tastes just changed. I'm not really strict, I will enjoy a bit of cake here and there, but I don't buy sweet things in much, and now I find if I eat cake half a slice and I start feeling nauseous. It's hard at first but you start really tasting the healthy food and it's much better. Throwing that much sugar at your body can't be good for it at all.
Sorry that turned out to be really long!!