I don’t find it strange. You mentioned boats as an example. A military ship will naturally have many more crewmen than a merchant ship because it is designed for a very different job. Even during the age of sail, a merchant ship or whaler might have only 12 to 20 crew, while a military ship of similar size would always need 4 men per gun. By way of counter example, a modern aircraft carrier has 4000 to 5000 crew, because it is essentially a floating airport. About 40% of these crewmen are for flight operations alone.
Some of your other examples are not new at all. A plane doesn’t really need more than one person to operate at any point in history, although they did often include dedicated navigators and flight engineers for safety and convenience. I also can’t recall trains ever needing more than one engineer. There just aren’t any other tasks that need to be performed. A second engineer might be desirable, but they really only exist in case the first one gets tired or something.
It’s not a matter of a reduced staff, but that modern, highly mechanized and computerized facilities need very few people. For example, watch one of the episodes of the program How It’s Made, and you may notice how few people there are in many factories. A giant plant that makes gypsum wallboard or cans vegetables will have maybe a handful of employees.
If you’ve ever worked in the financial department of any business, people are usually your biggest expense by far. Anything you can do to shave even a few people off the payroll results in big savings which is why the modern American corporation is obsessed with efficiency.
People like to point to technology and stuff like robots because that stuff is tangible but a lot of the gains actually come from better management practices. As much as people poo poo things like ISO 9000 and Six Sigma, it’s ideas like them that have resulted in the modern workplace with just a few people doing lots of things.