We all contribute to making this happen. We want food to be cheap and bought in one place so can take the car and load it up easily so we use supermarkets.
They want to maximise their profits and keep their costs as low as possible so they build big units with huge car parks, pay suppliers as little as possible, buy massive amounts to get stuff even cheaper, and they dominate the market. They waste huge amounts of food.
Producers have to cut their costs to deal with supermarkets - and there is almost no one else left to deal with except the companies that produce for supermarkets who also want stuff as cheap as possible.
The days of farmers employing people on farms from local land workers have long gone - there is no job security at all, it is all seasonal, and they are paid on the basis of how much they pick. Other jobs are done by machines now so there is no year round work. British people won't do the work - it is often cold, dirty, very physical, long hours and poorly paid.
A lot of what was traditional farming has become corporate farming with animals kept penned up constantly in big industrial units for milk and meat production. Millions of gallons of milk are poured away every week because we don't need it - and the EU subsidises the businesses for it.
If we were prepared to pay more for food, and avoided supermarkets, used our local high streets, lived on what is in season instead of wanting strawberries in January and other things that are imported out if season, we could have a better British farming industry and workers could be paid more. Farm workers often had tied cottages- very rare now, they are usually turned into holiday lets.
Our demand for cheap food, processed crap, and convenient one-stop shopping created this.