I can't speak to it, but I do know that icebreakers aren't in the same maritime class (I forget the specific term here?) as those other ships. There just might not be somebody who checks both boxes.

I used to be an officer of the deck on navy ships. From liking at the bridge and knowing the history, it looks like a very narrow and technical route under the bridge, and probably slow and prone to wind. At slow speeds, it’s difficult to get steerage due to less water over the control planes, so without auxiliary thrusters it’s hard to control. That means you need both familiarity with the local conditions and also with the ship and its dynamics. Going a few hundred kilometers is a day or less and it’s easier and safer, so it’s the best choice when there isn’t a compelling reason other than saving a bit of time once in a while. Maybe next time they’ll choose to do the training and certification, but this time they didn’t.

I think this article tries to make it sound like a huge deal, but no one really cares in reality.

> [Pilots] have training on some specific dangerous/technical passages/ports and are taken to a ship, pilot the ship through the passage or into a berth, then leave and go on their way?

My understanding is that Pilots never steer the vessel itself, rather they act as navigational experts that can be consulted in real time by the staff on the bridge.