But Hawaii is subject to the laws of North America, so I don’t see why it’s so weird to classify it as part of North America.
“North America” is not a legal construct, but a geographic term. The US can extend its laws wherever it likes, but it is not going to alter the facts of geography. The US can no more incorporate Hawaii into the North American continent than it can make the 49th parallel into the Equator, or make Mt McKinley the highest mountain on earth.
So Hawaii is part of America but not NORTH America?
America is also a geographic fact. You can say that Hawaii is one of the United States, or that it is part of the United States. You can of course use “America” as a synonym for the United States, but it’s not strictly accurate, and is liable to cause confusion unless the rather limited sense in whcih you use it is very clear from the context.
Hawaii is part of the country of the United States of America, which is a political entity, just like until 1946, the Philippines was a territory of the United States. But neither of those places are part of the continent of North America. Does that make sense?