Washington state resident here, living in a city next door to Seattle.
This is a new, tacked-on tax on top of existing B&O taxes, plus other taxes Amazon pays to Seattle for construction. So they are saying no to an extra tax, targeted at them -- they'd be paying around 30% of the total revenue generated.
Seattle government really is ultra-leftist: I voted for Clinton, Obama, Clinton but these people are like the rabid Bernie Sanders extremists who hate evil corporations while loving to spend their money. One of the Seattle Council members (who is trying to pass this) led an anti-Amazon rally awhile back, and has made public statements that corporations like it should be taken over by the government and their wealth distributed to "the people." She proudly identifies as a socialist. Elections are between left and even more left.
Seattle government is also on a massive and unsustainable spending spree, fed by the construction boom and huge increases in property taxes. Council staff was bumped up, spending on the homeless was already doubled before trying to add the Amazon tax, and they are wasting millions on feel-good dumbness like spending $2+ million to subsidize a failed bike-sharing program.
So if I did live there I'd be ranting even more about the poor leadership of Seattle, and why they should be spending the money they have more carefully instead of adding more and more taxes.
I see none of our liberal friends have anything to say about above. About how the real world of progressivism is compared to the make believe one of Paul Krugman or some other elite liberal think tank or other out of touch with reality elite liberals living in their isolated affluent paradises