The tax thing is relatively new. IIRC, it has something to do with WA requiring it across the state for online purchases. It has been in place since at least last summer, if not longer.

Because (I believe) the tax TR charges gets remitted to WA, when you go through the border, CBSA will tax you again to collect PST+GST. But they rarely ever slap you with duty, even though by the book they might need to.