Except as otherwise provided in this section, each employer shall pay an overtime wage of at least 1.5 times the usual hourly wage, computed in accordance with § 3–420 of this subtitle. This section does not apply to an employer that is: subject to 49 U.S.C. § 10501; a nonprofit concert promoter, legitimate theater, music festival, music pavilion, or theatrical show; or an amusement or recreational establishment, including a swimming pool, if the establishment: operates for no more than 7 months in a calendar year; or for any 6 months during the preceding calendar year, has average receipts that do not exceed one–third of the average receipts for the other 6 months. This section does not apply to an employer with respect to: an employee for whom the United States Secretary of Transportation may set qualifications and maximum hours of service under 49 U.S.C. § 31502; a mechanic, partsperson, or salesperson who primarily sells or services automobiles, farm equipment, trailers, or trucks, if the employer is engaged primarily in selling those vehicles to ultimate buyers and is not a manufacturer; a driver if the employer is engaged in the business of operating taxicabs; or unless a collective bargaining agreement between an employer and a labor organization provides otherwise, an employee of the employer if: the employer is subject to Title II of the federal Railway Labor Act; the employer does not require the employee to work more than 40 hours during 1 workweek; and the employee voluntarily enters into an agreement with another employee to trade scheduled work hours and as a result the employee works more than 40 hours during a single workweek.