Amongst other things it's a function of more mechanisation and more intensive farming techniques making food production more efficient. It's good in many ways as food is cheaper but it's not good for rural communities or the natural environment. The sort of small family farms that I grew up on can no longer be economically viable in reality. A farmer would have got paid more for producing a ton of potatoes in 1980 than (s)he would today so there is little point in planting a few acres like my Dad would have done. You need to be on a bigger scale than that.
I grew up in a rural area in the 1980s and the bulk of our groceries would have come from a shop a few miles away (think Arkwright in Open All Hours) and he went around all the rural houses in bay-window VW Type II van while his wife ran the physical shop, probably visiting maybe eight or ten houses each day with groceries and also coal, gas cylinders, possibly even bags of cattle feed and anything else someone might have ordered. Today, I see people leaving supermarkets with enough shopping to have almost fill a Type II VW and that is just for one family! Family sizes have generally got smaller, what are people doing with all this stuff?
I remember a Terry's Chocolate Orange being a real treat, once or twice a year at Christmas and Birthday and they were quite expensive. Even on a relatively modest wage, I could afford to eat two or three a day at today's prices if I wanted to.
Can't disagree with any of that. This is very definitely farming country out here - mostly arable and some market gardening. Everyone now concentrates on the staples of wheat, sugar beet, potatoes and oil seed rape. There's a lot less other crops being grown, like onions, carrots and celery - and the fens used to be very famous for their celery.
Certainly, something like a chicken used to be a Sunday / special occasion thing rather than an everyday meat. With intensive rearing, it makes it a lot cheaper - economies of scale and all that. There's a place up the road that rears ducks - they pump out I think it's 20,000 birds every eight weeks from just a small handful of sheds.
Likewise here. I'm London born & bred, but moved out here more years ago than I can care to admit. Well, mid 80s. The butcher's van used to come round twice a week, the milkie three times a week (he did bread, fruit juices and cheese as well) and a green grocer had a van too. A fish van used to turn up in the village on a Tuesday, and the pub sold eggs from a local supplier. Ely had a Co-op and a Tesco and that was it, but there was a good market twice a week. Now there's a Waitrose, a Sainsbury's, Iceland, Aldi and a much bigger Tesco.
I'm guilty of buying a lot of groceries (two peeps here chez Casa Reynard), but I typically only go shopping once a fortnight or once every three weeks.