Sometimes replay doesn't make a call any clearer - like whether Schilling touched the bag - it LOOKED like he grazed it - but there wasn't anything that was conclusive about it, and personally (this is without bias that I say this), that home-plate empire must be SOMETHING to watch the play at home, THEN look allllll the way over there and be so certain that he was out.
Those plays are so close, that unless you have some censor in the glove coordinating with a censor on the mound, there's not a way to be absolutely sure about it. I'd prefer that human error come from the players, but that's how the game works, and every team gets gypted at some point, so eh, it evens out?