Maybe the next big step is creating AI-driven cargo ships that can independently get stuck in the Suez canal.

On a more serious note, I can't shake the impression that would be a logical next step for all long and medium distance freight, be it road, water, air or space. Whether it's a good or mature idea is anyone's guess.

I wonder if some of the classes are just easy to detect objects that they're using to assess the accuracy of the user.

There sure are: https://www.marksetbot.com/

Boats are on the road too. In the form of being on trailers, Etc.

Or sea planes. That was what I was asked for most recently.