"to make the boat look more uniform".... paint
But paint requires maintenance. In Alaska it's more than having an unpainted boat. It's sorta like part of the culture. Real Alaskans don't need that frilly stuff called paint that people down south use like women use makeup. And also it may feed a male identity need.
Painting a boat in Alaska is possible but it cuts into boating time. There's not much weather up there to paint in and most would rather be doing other things. And need to be doing other things. And if you spend the month of June painting and refitting your boat it likely will rain through July and August. It may even rain the whole summer long.
And there's probably another sackfull of reasons I haven't mentioned but up north they either pretend to like bare oxidized aluminum or they actually do and that's scary.
North Western Washington State USA