Not necessarily. Firstly because I don't actually think there is any requirement that maps are 100% accurate, Google never a claim made anywhere that they are flawless. Secondly because if the city / town / local authority hasn't put up signs, it's entirely possible that they haven't informed map makers either.

So map makers are not responsible for inaccuracies in their map, and even if they were responsible, they may not have been told.

There's levels of culpability and in this scenario Google seem to be right at the bottom, if on the list at all.