It seems to be a common law shared amongst most nations. It’s the same here. If you’re at a crosswalk, you’re supposed to get off your bike, wait for traffic to stop and then walk it across the street.
That being said, do I abide by this? No, not usually anyway. I have valid reasons for why, however.
For one thing, I live in a rural town where pedestrians aren’t all that common. During mid-day you’re lucky to come across someone every couple of hundred meters. The other reason is that motorists here are absolute jerks.
Legally, if a pedestrian is at a crosswalk without a traffic light, the car is supposed to stop and let the pedestrian cross. The drivers here absolutely will not stop for you regardless of whether you are on your bike, off your bike, or don’t have a bike at all. Therefore, it just makes sense for me to be able to get across the street as fast as possible before any cars get in the way.