Except as provided in subsection (b) of this section, a motor carrier permit is required for a passenger motor vehicle used in the transportation of persons for hire. A motor carrier permit is not required for: a motor vehicle used exclusively for the transportation of pupils to and from public or private schools; a motor vehicle operated for a period of not more than 3 months in any registration year in the transportation of persons employed at a cannery located in a county; taxicabs; public transportation for hire authorized to operate on the boardwalk in Ocean City; a vanpool operation as defined in § 11–175.1 of the Transportation Article; a local public transportation system established under a law enacted by the local governing body of a county or municipal corporation; subject to subsection (c) of this section, a motor vehicle used by a privately owned transportation company exclusively to provide transportation system services under a contract with the governing body of a county or municipal corporation or with a unit of State government; shuttle bus service operated by the University of Maryland, College Park Campus for students enrolled at the University of Maryland, College Park Campus and, in exchange for payment by a municipal corporation in which the University of Maryland, College Park Campus operates shuttle bus service, transportation service on the shuttle bus to residents of the municipal corporation; or transportation services that a nonprofit organization provides through the use of a volunteer driver and the volunteer driver’s personal vehicle. A privately owned transportation company that provides transportation system services under a contract with the governing body of a county or municipal corporation or with a unit of State government shall obtain a motor carrier permit for motor vehicles that the company does not use exclusively to provide transportation system services under a contract with the governing body of a county or municipal corporation or with a unit of State government. The public duties of a common carrier may not be imposed on a person with respect to a vehicle for which a motor carrier permit is required under this section, if the vehicle is not actually engaged in public transportation.