In any county containing a population of 4,000,000 or more, the board of supervisors by appropriate rules may provide that nonprofit hospital volunteer groups and hospital auxiliaries recognized by such county may install and operate gift shops within medical and health facilities owned or operated by such county. The board of supervisors may permit the use of such facilities for the purpose provided herein without the necessity of competitive bidding or the charging of a monetary consideration therefor. The net proceeds derived from the operation of a gift shop shall be used solely for the benefit of patients confined within the medical or health facility containing the gift shop.