Whenever any county, city or town imposes a license tax on merchants, the same shall be in lieu of a tax on the capital of merchants, as defined by § 58.1-3509; however, no county, city or town shall be required to impose either a license tax on merchants or a tax on the capital of merchants. The prohibition under this section shall not extend to short-term rental property as defined under § 58.1-3510.4.