Another good example to be considered in the debate mill. The leakage here is that the rule doesn't say what the calling player will WIN, only what they will lose. At the 2011 Summit we found the inequity that some proposed rules allowed a player to win the entire actual amount but only lose the dealer counted amount... an unacceptable irregularity.
I'm not so sure why the amount that the bettor is bound to lose must necessarily be the same amount that the caller is bound to lose. Is it just because the amounts are different? (1)
The all-in player has decided to risk all of his chips by going all-in, if he loses to a bigger stack he expects to be eliminated. (2)
On the other hand the potential caller may be relying on a count of the dealer and expects to lost that amount. The expectation of both players are met, even if the amounts to be lost are different. (3)
I'll take the view that poker iis an even-money gamble:
1: It's b/c poker is a game of even-money bets, unlike craps / roulette, etc. where you can win more or less than you bet, depending on the odds of the specific bet you make (i.e. the payoff on a craps bet on 6 is much different than the payoff on a bet on 4). In poker if I bet you 25, and you call we both expect to win or lose 25 (x the total number of calling players). This also keeps the evolution of the pot odds during the hand consistent with even money on all bets. If under this one situation I can win 25 but only lose 20, then the pot odds of the bet are fundamentally changed.
2: But he expects to lose all of his chips if he loses, but win an equal amount if he wins. Again, if he can lose 100% but only win 80% he's not making an even-money bet.
3: If poker is a game of even-money bets, which I think it is, then the expectation should always be I can win the same amount as I can lose... and the amount should be the same for both players. Otherwise it's not an even-money bet between the players involved.
The 2011 Summit was very interesting on this, there were proposals which would have resulted in the possibility of uneven bets... no conclusion was reached on this b/c accepted action was adopted instead, and accepted action by it's nature is even-money everytime. The discussion will continue...