Firstly, I'm a cyclist in Auckland.

As for the undertaking law only being for cars, no it isn't. The Road Code is for all vehicles unless stated otherwise. Cyclists must observe the same rules as cars / truck / horses and carts etc.

The best fix to Tamaki Drive problem is a dedicated cycleway. The standard for a 2 way cycleway is a minimum 2.5m. Removing the kerbside parking would enable this to happen. Getting back some grass / kerbing etc would enable a full 3m cycleway.

And the cyclist made the choice to illegally undetake the moving truck.