This article does not apply to a collectively bargained Taft-Hartley self-insured prescription drug plan offered pursuant to the federal Employee Retirement Income Security Act of 1974 (29 U.S.C. Sec. 1001 et seq.) or to a pharmacy benefit manager’s provision of pharmacy benefit management services pursuant to that Taft-Hartley plan. To the extent a pharmacy benefit manager is providing services for other payers in addition to a collectively bargained self-insured plan that provides prescription drug plans governed by federal law, this article shall apply to the pharmacy benefit manager in its performance of pharmacy benefit management services pursuant to those other payers.