This subtitle applies only to: a code county in the Eastern Shore class; Anne Arundel County; Baltimore County; Calvert County; Cecil County; Charles County; Garrett County; Harford County; Howard County; Prince George’s County; St. Mary’s County; Washington County; and Wicomico County. This subtitle is self–executing and does not require a county to enact legislation or, if applicable, to amend its charter to exercise the powers granted under this subtitle. The powers granted under this subtitle: are supplemental to any power granted by another law; and do not limit any other power. This subtitle is necessary for the welfare of the State and its residents and shall be liberally construed to effect the purposes stated in § 21–504(a) of this subtitle.