I don't think anyone has an issue with concept that if there is an invalid click then it is fair that you not receive a benefit from the click. The problem as I see it is that publisher see the value of earnings (estimated) in their accounts go up, then (in near time, or at the end of the month) they see that value reduced. As if AdSense was taking money from them.
The real problem is that this is situation where one has a compounding of the two of the most difficult to avoid cognitive biases. Anchoring and Loss aversion. By showing an estimated amount for estimated earnings in your account, Adsense anchors a number, say $1000, you are now certain that you should get at least that amount. Moreover, for those that check their accounts frequently, one also see a number that is consistently increasing. So your expectation is that the next time you check the value has increased.
Now when AdSense reduces the amount, not only does it not meet your expectation you also feel like something was taken. Even if the first time you check the amount it is much higher than expected, if the next you check the amount has dropped you still feel slighted. This is loss averion.
What is the alternative, Adsense could not report "estimated earnings", it could simply send you check at the end of the month. You'd get what you get and you wouldn't get upset. But you have far less transparency. AdSense is being transparent, they have no obligation to do so, if they really wanted to steal from you then why would they show you that they are doing in it?
Who knows if they return monthly claw backed money to advertisers or put it in their own pockets.
It would be unlikely that advertisers are returned money, as they are likely never charged for the invalid clicks in the first place.
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