Whyever wouldn't they want to show how much money this is bringing i-

oh, that's why.
That leads Coombs and other gun tax opponents to wonder: How much money has Seattle collected from this tax? It's the subject of a lawsuit filed by reporter Dave Workman and the Bellevue-based Second Amendment Foundation in September.

In the spring, Workman sought the city's tax revenue from the gun violence tax, but the city government declined to divulge the information, claiming that such records could compromise the identities of the people who have paid the tax.
Which is bullshit, but it's the excuse they chose.  Because that's much better than admitting their "It makes me feel virtuous!" tax is driving business to other cities.