Subject to subsection (b) of this section, this subtitle only applies to: each charter county that engaged in collective bargaining with an employee organization prior to October 1, 1994; Charles County on or after October 1, 2017; and each municipal corporation that engages in collective bargaining with an employee organization prior to October 1, 1995. This subtitle may not be construed to repeal or limit any local charter provision that extends collective bargaining rights to employees of employers and, if a local charter authorizes or grants collective bargaining rights to any employees, the provisions of this subtitle do not apply. This subtitle may not be construed to: require any form of collective bargaining; require any method, means, or scope of bargaining between an employer and an exclusive representative; or authorize binding interest arbitration.