Sorry I've never play at a Blackjack game so I can't tell (in fact I've never played at any Casino game at all because I hate to gamble when I know I don't have superior edge)
I'm rather referring to Casino's game everybody knows: Roulette while betting on red or black (at least I know that). There are 37 numbers for european roulette and 38 numbers for American roulette so that the probability of winning at each bet is
p=18/37=48.65% for european roulette
p=18/38=47.37% for american roulette
so the edge of the casino is only
q=50%-p=1.35% for european roulette
q=50%-p=2.63% for american roulette
Just remark that US casino roulette are nearly double more edged against a player than a European casino roulettestill 2.63% is far from your 25% (btw are you sure it is 25% for Blackjack because I don't understand why people would be so stupid to chose something that is much more edged against them than roulette ? Or you use a definition of edge that is yours ?) !