Except as otherwise provided in this Section, the corporate authorities of any city of 1,000,000 or more inhabitants may, subject to the provisions of “The Illinois Vehicle Code”, as now and hereafter amended regulate, license and prescribe safety requirements for motor vehicles used to transport for hire students to or from a school where students are in attendance except (a) those belonging to or used by a common carrier or public utility operating under the jurisdiction of the Illinois Commerce Commission, and (b) those under the jurisdiction of the State Board of Education or owned by the Chicago Transit Authority. However, no such municipality, including any home rule unit, may require that school buses be equipped with seat safety belts while transporting students who reside and attend schools situated outside of the corporate limits of the municipality, and it is declared to be the law of this State, pursuant to paragraph (g) of Section 6 of Article VII of the Illinois Constitution, that this amendatory Act of 1986 is a limitation on and denial of the powers of a home rule unit to impose such a requirement. In this Section “school” means any public, private or parochial elementary or secondary school or nursery.