I think it should work like this: government buys everything zoned as a store, restaurant or pub at a deliberate unfair rate. Create A budget for maintenance.

If you want to open a store you wait for a vacancy and apply. Citizens may vote for the applicants, the closer you live the more weight the vote has.

Count the store visitors and set some reasonable minimum. They don't have to buy anything. To much traffic would give priority for a larger building.

The first n square meters is free (smallest building). Low rent for anything above.

People want a tea room but you can't survive doing that unless you price the hot water absurdity. You can have lots of small shops selling eye candy. They don't have to sell a lot of wooden dragons, as long as it attracts visitors it's good to have.

It will be a town or city in the least boring percentage.