I understand that 'some' people may be both cash and time poor, but I believe the number 'actually' working two jobs, 50 plus hours a week, is relatively small compared with the number of people who have shitty diets and eat rubbish food.
I would be fascinated to see a Venn diagram of where these populations intersect.
I would maintain that good wholesome food, if not the actual bestest quality imaginable, is still accessible to anyone outside of a rural area, for way less than 'fast food'
I was a student once. Fast food was a rare luxury. I still managed to eat well.
Education is the key, and though it should be a parental responsibility many adults simply don't have the knowledge or wisdom to teach their kids.
Again you are thinking about how easy it was for you as a single person to access good quality, cheap, healthy food, multiply that by 4; and students do tend to have a lot of spare time on their hands in my experience. It is a logistical problem as much as anything else for many people.
Most people, if they put their mind to it, could probably find a way to do this but I imagine many cannot be fagged with the hassle and don't care enough about their diet as they have a list of rather more pressing problems to deal with. Getting the correct amount of money set aside for a weekly shop and trying to sort out the necessary transport to move it is going to get tedious after a while.
Jack Monroe the single mother who blogged in the Guardian about how to feed a family healthily on low incomes covered all of this. Often the desire is there but people are just simply put off by the hurdles in their way which do not exist for people on middle incomes - lack of transport, lack of time, lack of access to the sums of money that allow big weekly shops.
All I am suggesting is a bit of empathy for people in this position. They are not all lumpen Proles who are too stupid to feed themselves properly.
And if the generational knowledge that teaches these skills has been lost it does need to be taken up by the state what ever Toby SmallState thinks, I wasn't just taught to cook by my parents I was taught to cook at school, and sow and knit. This is part of the rather snooty attitude that school is only for academic skills and, worse, supposedly feminine skills like cookery don't even have a place in the practical arena; as I doubt Toby would send out a stentorian blast proclaiming the family is the place to be taught woodwork. I bet there are many more cooks in this country than carpenters.