I am in complete agreement with your observation. However, on the Great Lakes, 1000 foot ships that can carry 50,000 tons of coal or iron ore are called boats-it is a long tradition going back many many years. Even the officers and unlicensed mariners call them ore boats or “lakers” in contrast to ocean going ships, aka “Salties” that load or discharge cargo at Great Lakes ports.
The big ore boats are too big to pass through the Welland canal and also were never built to sail on the oceans.
As a kid, my parents used to take us to visit the two parallel sets of triple, directly connected locks on the Welland Canal to watch the action.
I think we used to call the locals Lake Freighters.