First of all, giving way means don’t get in the way.
There was this thread on the bicycles network forums called the ‘Dumb Cyclists and Pedestrians Thread.’ At one point, someone claimed that turning vehicles must give way to pedestrians even on a red pedestrian signal, and furthermore claimed that turning vehicles must give way to pedestrians even on a green arrow.
That poster’s basis is that the actual law just states a requirement to give way to pedestrians, and not even saying anything about green arrows. Now I am quite good at taking written rules literally, and I did not think a rule worded like that would be relevant on a red pedestrian signal, nor does sounding the horn at a pedestrian when turning on a red pedestrian signal, especially on a green arrow, seem to go against the spirit of the rule.
Someone did claim that law needs to be changed but was told it could not be because vehicles need to not base decisions on pedestrian lights. Removing the requirement to give way to pedestrians on a green arrow is sure to make it clearer.
Now there is a requirement for bicycle to give way to pedestrians on shared paths, but if that does not apply on bike-only paths, why does the requirement for turning vehicles to give way to pedestrians apply even on a green arrow. There is not requirement to give way to pedestrian when going straight through on a green light.