The following hand data is taken from Mastering Small Stakes No Limit Holdem by Jonathan Little. Both hero and villain have known starting hand ranges that narrow as they get to the river. Below, I post only the ranges as they are at the river (since it seems irrelevant what the starting ranges were, unless I'm missing something).
Hero's River Range. Suppose hero is on the river and decides to bet all in $141 into a pot of $121 with the following range:
The author then comments:
And then here is the range that villain should call down with according to the author:
Notice here that villain is calling with (roughly) the top 35% of his range (technically, it's the top 39% of his range; the author later mentions that to achieve a perfect 35%, villain can remove some combinations of AJo).
Question: Why should villain only call with the top 35% of his range in this example? Shouldn't villian call with 100% of his premium hands (for value), and with 100% of his bluff beaters (expecting to win 35% of the time with them, per hero's strategy)?
Notice that in this particular case, 100% of villain's range are in fact bluff beaters or better (far greater than 35%), in that they beat hero's QJo bluff on the given board (Ah, Kc, 5d, 3h, 7s)!
So again: why should villain call with the top 35% of his range when 100% of his hands are bluff beaters or better? More generally, why should a rational poker player call with the top X% of his range when being laid X% pot odds (by an opponent playing perfectly GTO)?
EDIT. I thought about this some more. To make the math easier, let's now assume that hero bluffs with 100% of QJo (and not just the right amount of them to achieve a 35% bluffing frequency). Then it follows that hero's range will consist of 44% bluffs and 56% premium hands. Assume now that hero bets in such a way that he lays villain with 44% pot odds (instead of the 35% talked about above).
Then the following principle is true:
(P) Villain should call with any hand that gives him 44% or more equity against hero's range (KK+, AK, and QJo).
Here is the equity of each of villain's hands that he could call with:
As you can see, it is rational for villain to call with 100% of his river range! This is far greater than the top 44%.