*puts scientist hat on*

Your list is biased and therefore doesn't show people an accurate picture of rates. It will not pass peer review.

One, you seemed to focus on one area. Seattle might have a reason for doing what it's doing. Or the Dommes you chose to include or not include.

Two, there are many Dommes who don't post their tributes. Some are new and some have been doing it for a long time. This can be because the law prohibits it.

Three, I assume Dommes have some variance in what they might offer in their tributes, increasing it if certain things are requested. In other words the $320/hr you see might actually not include your fetish or some outfit or something.

There is a general national rate. It's about $400/hr. It goes up and down based on various factors. Location and its standard of living; skills and if any of them are specialized, complicated, or dangerous; experience; reputation; dungeon; etc.

My idea about tribute is that Dommes who started before the current rate may not raise their tribute as it increases and it's why they seem "cheaper". Newer Dommes, some of whom are the FetLife/Twitter/I-saw-this-on-Netflix people, hear the national rate is X and start their tributes at that, even when they really shouldn't. A new Domme with little to no experience, no established reputation, who's running sessions out of a hotel room shouldn't be charging the same as a 20-year, well-known professional with an amazing Dungeon. But that's how capitalism works.