(a) The commissioners court of a county may authorize the payment of reasonable travel expenses incurred by a person who:
(1) is an agent of the county, or is a board or committee member appointed by the commissioners court; and
(2) is not a county or precinct officer or employee whose travel expenses may be set under Section 152.011.
(b) The travel expenses must be incurred by the person while performing county business authorized by the commissioners court.