Except for operations pursuant to a contract authorized by sections 75-303.02 and 75-303.03, it shall be unlawful for any common or contract carrier by motor vehicle subject to the provisions of sections 75-101 to 75-155 and 75-301 to 75-322 to engage in any intrastate operations on any public highway in Nebraska unless there is in force with respect to such common carrier a certificate of public convenience and necessity, a permit to such contract carrier, or a permit to a transportation network company under section 75-324, issued by the commission which authorizes such operations.