(a) A common carrier by motor vehicle shall not deliver or relinquish possession at destination of any freight transported by it until all tariff rates and charges thereon have been paid except under such rules as the Arkansas Department of Transportation from time to time may prescribe to govern the settlement of all such rates and charges, including rules for weekly or monthly settlement and those to prevent unjust discrimination or undue preference or prejudice.
(b) However, the provisions of this section shall not be construed to prohibit any such carrier from extending credit in connection with rates and charges on freight transported to the United States, for any department, bureau, or agency thereof, for any state or territory, or political subdivision thereof, or for the District of Columbia.