If its a requirement in some countries, why do some airplanes have them, some not - same type, same airline of course.
Example: Some SIA Jumbos are with, some without these red markings.
Virgin Atlantic had it on most airplanes in the old livery, but not on the new one.
You mention VH- registered planes carrying these stickers. I cannot remember to have seen a Qantas 747 here in FRA with them.
Cathay Pacific yes, but not on B-HOX, the allgreen Jumbo.