why is this so confusing to so many umpires?

[Dave Reed]

Steve, I'm going to quibble here. If the ball strikes the bat first, and then a finger, I think it is a batted ball which subsequently strikes the batter.

By common interpretation, a batted ball which strikes the batter, even if in the forward part of the box which is actually fair territory, it is a foul ball.

I can't support a call of fair when the ball strikes the batter. Either it is dead because it hit the batter first, or foul because it hit the batter second.