In OZ they do yes ALL males have large cupped and ALL females have smaller flat wattles, 100% when sexed correctly by a pro breeder.
Why would a 'pro breeder' have to do the sexing to be 100%, seems like anyone could sex them 100% if what you say about the wattles held true...
I can say without doubt it certainly doesn't hold true with my Guineas, and I find it hard to believe the gene pool is so tight and perfect in any country that it holds true...