They’re effectively monopolies.
Often, those mourning the loss of the local butchers etc. seem to overlook the fact that having “everything under one roof” (supermarket-style) is hugely convenient.
What about actually having an out-of-town real market. i.e. lots of food retailers under one roof; a one-stop shop with real competition.
(Supermarkets should be forced to remove the word “market” from their names)