(a) Subject to Chapter 101, Civil Practice and Remedies Code, the following functions are public and governmental functions, exercised for a public purpose, and matters of public necessity:
(1) the acquisition of an interest in real property under this chapter;
(2) the planning, acquisition, establishment, construction, improvement, equipping, maintenance, operation, regulation, protection, and policing of an airport or air navigation facility under this chapter, including the acquisition or elimination of an airport hazard;
(3) the exercise of any other power granted by this chapter to local governments and other public agencies, to be severally or jointly exercised; and
(4) the acquisition and use of property and privileges by or on behalf of a local government or other public agency in the manner and for the purposes described by this chapter.
(b) In the case of a county, a function described by Subsection (a) is a county function and purpose. In the case of a municipality, a function described by Subsection (a) is a municipal function and purpose.