A county commission may, by ordinance, impose upon and collect from the users of emergency ambulance service within the county a special service fee, which shall be known as the "special emergency ambulance service fee." The proceeds from the imposition and collection of any special service fee shall be deposited in a special fund and used only to pay reasonable and necessary expenses actually incurred and the cost of buildings and equipment used in providing emergency ambulance service to residents of the county. The proceeds may be used to pay for, in whole or in part, the establishment, maintenance and operation of an authority, as provided for in this article: Provided, That an ambulance company or authority receiving funds from the special emergency ambulance fees collected pursuant to this section may not be precluded from making nonemergency transports.