In the UK there are more players, but the game is essentially the same.
Price-fixing by colluding with the competition is illegal in both countries, but regulation is effectively powerless. The supermarkets are both politically connected, and in a position to cause voters pain.
There are many more grocery options in the US. Walmart does have some pricing power, but not much since it’s in the single digit percentage range at most, and it results in low single digit profit margins.
Meaning if Walmart tried to use their pricing “power” to increase prices more than a couple percent and earn more net income, shoppers would go elsewhere.
In Australia, there's basically a cartel of 2 supermarket chains (Coles and Woolworths) and they control all retail pricing of groceries.
https://www.farmdrop.com/blog/how-supermarkets-ruined-dairy/
In the UK there are more players, but the game is essentially the same.
Price-fixing by colluding with the competition is illegal in both countries, but regulation is effectively powerless. The supermarkets are both politically connected, and in a position to cause voters pain.
The position might be different in the USA, I don't know. I would suspect not - this article suggests that Walmart has considerable pricing power: https://www.businessinsider.com/walmart-low-price-strategy-t...