Supermarkets and Localism

From the BBC

A group of local councils in England is formally asking the government for new powers to tax large supermarkets.

BBC News has learned that Derby City Council has called for the right to bring in a levy as a "modest" effort to ensure supermarket spending "re-circulates" in local communities.

I don't understand this need for money to stay in the local community. Take 3 products: bacon, watercress and lamb. I happen to know that they're produced in large abundance in Wiltshire, Hampshire and Wales respectively. So, the stores in Swindon are giving money to Hampshire and Wales, the stores in Winchester are giving money to Wiltshire and Wales and the stores in Cardiff are giving money to Wiltshire and Hampshire. Everyone's buying stuff from everyone else, so not much spending stays locally, but arithmetically, each spending money on each other nets off.