Funny Aussie traffic lights

Some road traffic lights on Perth streets turn from red to flashing yellow then to green; and cars are supposed to start moving when it starts flashing yellow. I never understood why there was a need for this. What's the problem with just going straight to green? What's the inside joke? I was reading today the road rules because I'm driving next week, and found out that these lights are called pelican lights! It's really funny because the flashing lights mean PROCEED WITH CAUTION. You may proceed, but only if there're no pedestrians crossing. This is the sort of thing I find exceedingly hilarious, although I have no idea exactly why. Pelicans are also my favourite birds; they are the most graceful when they use up the huge length of waterway for takeoff, and when they do their spirals in formation flying at high altitudes with their huge wingspans of I think more than 2 metres...