It is mainly only called when there is a situation like last night where it effects the outcome of the play. Bottom line, the way the rule is written, the baserunner has to know where he is and get the lane on a ball up the line like that. Mainly on plays where the pitcher or catcher field the ball.
Some guys, like Brett Gardner, are very good at getting to the outside lane. I guarantee that ump doesn't make that call if the runner was closer/inside to the running lane. If the Nationals were honest with themselves, they know the rule was correct, they were upset that it was enforced on that crucial play.
I have played a lot of baseball in my 41 years, and still play in multiple adult wood bat leagues and tournaments. Calls like this suck when enforced to the letter.