https://www.thestranger.com/slog/2018/03…

To draw this much attention to the law while neglecting to comply would be characteristically hypocritical and foolhardy — but I’m guessing the real answer is that they’re not significant enough an advertiser to matter to the City. If so, that’s got to sting.

If my guess is correct and The Stranger is exempt, I suppose the pitch/spin to future political Seattle ad-buyers would be “Any money spent at our paper goes undisclosed!” The obvious, unspoken reason would be “...because it is the advertising equivalent of a tree falling in an empty forest.”