(a) An authority created before 1980 in which the principal municipality has a population of less than 1.9 million may, with the approval of the governing body of the principal municipality:
(1) establish, operate, and improve a public parking area or facility in the authority; and
(2) set and collect reasonable charges for the use of a parking area or facility.
(b) An authority described by Subsection (a) may regulate public parking in public parking areas or facilities in the principal municipality under an interlocal agreement with the principal municipality according to which that power is delegated to the authority.