The legislature finds that the public health, safety, and welfare would best be protected by uniform regulation of hearing aid specialists, speech-language pathologists, speech-language pathology assistants, audiologists, and interim permit holders throughout the state. Therefore, the provisions of this chapter relating to the licensing of hearing aid specialists, speech-language pathologists, and audiologists, the certification of speech-language pathology assistants, and regulation of interim permit holders and their respective establishments or facilities is exclusive. No political subdivision of the state of Washington within whose jurisdiction a hearing aid specialist, audiologist, or speech-language pathologist establishment or facility is located may require any registrations, bonds, licenses, certificates, or interim permits of the establishment or facility or its employees or charge any fee for the same or similar purposes: PROVIDED, HOWEVER, That nothing herein shall limit or abridge the authority of any political subdivision to levy and collect a general and nondiscriminatory license fee levied on all businesses, or to levy a tax based upon the gross business conducted by any firm within the political subdivision.