If you have a look at the map I included, the section of Pambula Beach Road between the 60 and the 50 signs has houses and street lights most of the way along it. Don't know why the 50 sign was put where it was, seems arbitrary to me. In fact, from about where the 50 sign is onwards, there are no houses at all, only industrial units. So they obviously care more about Robert Smith Home Furnishings customers than they do about residents!
Don't know why they don't just make the lot 50 and be done with it.
It's OK to say "you should know the speed limit" but say I'm not a local (which, yes Pete, I am) and I hadn't passed a 50 sign, how would I know I was breaking the law? The surroundings don't look any different until you get into the main drag where the shops are.