We see lots of videos on the internet showing roads full of cyclists. However, one thing is that they all show the cyclists on the right (or incorrect) side of the road.
This video shows peak hour traffic in Cambridge, England. Cambridge has probably the highest bicycle modal share in the Anglophone world. I really hope in my lifetime I see something like this in New Zealand:
The other point to note is that, despite the impressive numbers, there is no separation of cyclists from motor vehicles. As in the Netherlands, you see that when there are enough cyclists on the road and the road is narrow enough, the dominance of the cyclists means cars have to navigate their way safely through the cyclists. It just proves that the more of us are out there, the safer it is!