Impossible to solve I’m sure. Probably lower priority than stopping them from putting lead in bread and selling cocaine snake-oil elixirs, or forcing them to list basic nutritional information on food packaging. Alas, we lack the tools to make businesses do or not do things.

By making it illegal? Brands can still compete on price and quality.

Grocery stores are a low margin business. If you make selling shelf space illegal, they lose that revenue and will have to raise food prices to stay in business. This isn’t a good outcome. I also question if the shelves would even changes much. They will probably prioritize their high margin products, which doesn’t sound any better.

Where does the money to pay for shelf space come from if not the money we pay for food?

In theory, sure. In practice, the food makers aren’t going to lower their prices to the stores, they will just stop paying the shelf fees.

What’s the legal way to arrange things on a shelf?