Zillow and Jackson County Real Estate

I am just a little amused by Zillow at the moment. I just watched a tutorial video about the accuracy of the Zestimate, and found that they keep track of how accurate they are on a state by state, and county by county basis.
So obviously I go to see how Jackson County Oregon rates…and wow…Zillow gives itself 3 stars (out of 4). Pretty good, huh?
So trying to figure out how good they are, I look at the numbers.
Of the houses that have sold that had “Zestimates”, 21% of them they were within 5% of the sales price.
An additional 22% were within 10% of the sales price.
Then an additional 22% were within 20% of the sales price.
That means 35% of the houses they were MORE than 20% off on.

So if you have a house they say is worth $400,000, there is a 35% chance that is worth less than $320,000.

That is not that accurate…