This is a brand new road!
Passing lanes few and far between, load of bends. Clearly, it wasn't engineered to mitigate this problem.
It was supposed to be the "scenic" drive, which means that people are going to be going slower on it, rather than using the Brand Hwy. (which suffers from the exact same problem but with more hills)
Someone designed it,
knowing how the road would be used with all the factors on road use being known and up to date (speeds, usage, growth). ie They weren't trying to shoehorn a new design over a crappy old roman road.
I remember the first time I used that road not long after if was finished. I was travelling out of peak usage just before holidays and could see the problem even without other cars on the road.
90,100,110,130 - it aint gonna make much of a difference in a head on.

Sure, say it adds 10 min to the trip or blame impatient/crap drivers all you like - people are people - the problem was entirely foreseeable and if the Govt
truly believed in their Towards Zero strategy then the road would've been build with engineered controls in place from the outset - not trying to bandaid it after the fact.
A more cynically minded person would figure that the revenue collected from the now "speeding" motorists would pay for the band aids.