You can’t make more land, it’s a finite resource. So the little we have available has to be turned to a variety of uses - food production, housing, business, industry, energy production, army & defence bases, hospitals, cemeteries, roads, railways, airports, gravel extraction, water treatment etc.
Part of the problem is wealthy people buying up farmland as a tax dodge, but it’s also housebuilders buying land that doesn’t have planning permission in the hopes that one day it will.
Near me there’s a farm that is currently in the local consultation for expansion of the town. That farm was bought 20 or 30 years ago by a big developer who then leased it to the farmer for agricultural production. It’s never had planning permission. Angela Rayner’s call for sites has meant the local council now has to consider it. In the last 10 years the town has increased in size by about a third, all of it on previously productive agricultural land.
Plus, as well as the agricultural land disappearing to developers, as it gets buried under a layer of tarmac the water can no longer percolate through, so it runs off somewhere else, somewhere it shouldn’t be. That’s often other farmland which now has twice the amount of water trying to drain and so starts to flood which it never did before. Flooded land can’t be farmed. Double whammy.
Farmer’s can’t compete with Big Businesses, and those with the deepest pockets sets the price and buys the land.