Any code city which imposes a license fee or tax upon business activities consisting of the making of retail sales of tangible personal property which are measured by gross receipts or gross income from such sales, shall impose such tax at a single uniform rate upon all such business activities. This section shall not apply to any business activities subject to the tax imposed by chapter
82.16 RCW. For purposes of this section, the providing to consumers of competitive telephone service, as defined in RCW
82.04.065, or the providing of payphone service as defined in RCW
35.21.710, shall be subject to tax at the same rate as business activities consisting of the making of retail sales of tangible personal property.