A lot of the two generations that are younger than I (under 70) have never really learned to cook and don't like doing so or shopping. And the really young people 18-30 age group probably got into the habit of takeaway food while studying and find it easier than shopping and cooking.
How they afford frequent takeaway, I do not know, but if they neither shop for food, nor have a freezer, it may be possible to balance a budget consisting of takeaway three or four times a week, and simple things like fried eggs and bacon, or cheese toast on the other day, or simply heating a tin of soup.
It would really be interesting to hear from the people who do live mainly on takeaway how they balance their budget.