Perhaps because the default state of Kindles is to be ad-supported.
I can think of no online store that would be particularly likely to attract people selling the non-ad-supported Kindles.
I do not believe anyone is keeping tabs in the sellers either -- though I could be wrong.
Based on previous threads, I got the impression that you do not live in the US.
If that conclusion is correct, you should be able to get Amazon to remove the ads for free.
If I am wrong, sorry.
