It should have been a common-sense, "Of course they need to." One need not have been a driver for very long to have seen that highway signs, especially on freeways in the large cities that are many truckers' destinations, are far more complex in vocabulary and grammatic content that just "Stop" or "Yield".
I'm kind of curious how San Jose Mayor Mahan answered the Q, if he was asked. I can't vote in San Jose mayoral elections, but Mahan, who is Lib/Prog, is a bit less isolated from daily street- and freeway-level daily realities than Steyer or Porter. I doubt that Mahan or Becerra have a chance.
Sheriff Bianco's answer could have been entertaining, since his officers are on Riverside County's streets, roads, highways, and freeways pretty much 24 x 7 x 52, and he can be pretty direct/blunt.