I used to live in Vancouver, Washington, and every place I went to shop asked me if I was an Oregon resident. (Of course, I groaned that they would have to go ahead and tax me.) That didn't happen when I went to restaurants, because I was eating the meal in Washington, and that would have been the case for you if you were traveling in WA yourself. The exemption is only for things that it was presumed you'd be taking back to Oregon.
Isn't that the same thing with items you wished shipped to states that online retailers were authorized to collect sales taxes for? The presumption is that you'd be using or consuming those things there, and not in Oregon.
As a side note, if this goes through, expect many fake Washingtonians to "move" to post office boxes in Oregon! If I were still back there, you can bet that I'd be one of them!
Yes, having lived in Portland and being so close to Washington, I know all about sales tax issues... LOL..
A follow-up here...
There was even a time, many years ago, that I got a “Tax-ID-card” (can’t remember what it was called, though) — in order that, being an Oregonian, I would not have to pay sales tax in the state of Washington. It worked and whenver I showed it, I would not have to pay the sales tax.
But, that was a very long time ago, and I gave it up and figured it just wasn’t worth the continual hassle. I paid the sales taxes after that... :-)