fair enough, as a Washingtonian I sometimes forget that others have to deal with state income tax, definitely makes sense it'd just be part of yearly tax paperwork you already have to do.

From a quick google I think a lot of the additional confusion is the mix of Use/Sales tax when they mostly (as a customer) have the same meaning but for a tax authority have different meaning, searching for "Washington how to declare sales tax" turns up a bunch of random stuff about regulations for retailers showing sales tax correctly, if you search for "Washington how to declare use tax" actually brings up the correct documents from the state, I can def see some bureaucrat not connecting that that's what was actually meant.