Nothing in this article prohibits either of the following:
(a)
Any county from designating the districts or zones in which advertising displays may be placed or prohibited as part of a county land use or zoning ordinance.
(b)
Any governmental entity from entering into a relocation agreement pursuant to Section 5412 or the department from allowing any legally permitted display to be increased in height at its permitted location or to be relocated if a noise attenuation barrier is erected in front of the display or if a building, construction, or structure, including, but not limited to, a barrier, bridge, overpass, or underpass, has been or is then being erected by any government entity that obstructs the display’s visibility within 500 feet of the display and that relocated display or that action of the department would not cause a reduction in federal aid highway funds as provided in Section 131 of Title 23 of the United States Code or an increase in the number of displays within the jurisdiction of a governmental entity which does not conform to this article. Any increase in height permitted under this subdivision shall not be more than that necessary to restore the visibility of the display to the main-traveled way. An advertising display relocated pursuant to this subdivision shall comply with all of the provisions of Article 6 (commencing with Section 5350).