@MidAtlanticDad posted:NFHS rules state that your foot can't be touching the ground outside of the chalk box. On the line is ok, but not over the line. Like @adbono says, maybe the box was so poorly placed that the ump let it go... or maybe he just didn't care.
Any part of the foot on the line is considered in the box. The location of the line - correct or not is not addressed in the rules other than the field set up. If that is not addressed before the start of the game, then the lines are official as they lay. Its a stradegy some use to make the pitcher uncomfortable and make him throw balls. If the pitcher isn't comfortable busting the batter inside, then a lot will likely be off the plate and called a ball. Keep in mind - a batter hit by pitch that is in the strike zone is a strike, the batter is not awarded 1st. Gotta have the right ump behind the plate to make that call.