Notwithstanding any provision of law requiring uniform property tax rates on real or personal property within the town, a town may establish subordinate service districts to provide and finance a governmental service or function that it is otherwise authorized to undertake. A function or service to be provided may include a function or service that the town ordinarily provides throughout the town only to the extent that there is an increase in the level of the function or service provided in the service district over that provided throughout the town.