In this situation, the dealer should check her whole card (or draw one card in NHC games) and push if she has a blackjack, right? Does anyone know of a game where the dealer would always pay the player regardless? I ask because I have seen this behaviour in some software.
My calculation:
P(BJ) = 1/21
P(dealer 10, A) = 4/13*1/13
Extra payoff = 1.5
Advantage = 1/21*4/13*1/13*1.5 = 0.17%
Seems a bit high?