That's what I'm saying, food deserts are strange places where import costs, supplier contracts and shipping logistics means that lentils are expensive and tuna is comparatively "cheap". Just 250km away lentils are a pittance and tuna is a reasonable expected price. ($1.50 for 100g of tinned tuna is average almost everywhere across metropolitan areas in Australia from my quick look at swapping my postcode around on woolworths, small town IGA is harder to check because they're independent, so I've only got my local metro IGA and my father's remote IGA as reference. My local metropolitan IGA price matches Coles and Woolworths pretty closely, but it's the wild west once you're out malee)

The idea that food is the price it is and that's the price to expect everywhere is how small communities in food deserts end up slipping through the cracks when grocery prices shift in either direction in larger population centres.