I suppose it is because something can be before you without necessarily facing you? Which of the two words implies "facing"?
I ANSWERED "I AM BEFORE YOU.", BUT MY ANSWER WAS MARKED WRONG, AND THE CORRECT SOLUTION WAS BOTH "I AM BEFORE YOU." AND "I AM IN FRONT OF YOU."
AT THIS STAGE IN THE COURSE, ARE WE SUPPOSED TO PROVIDE BOTH ALTERNATIVES IF THERE ARE TWO POSSIBLE SOLUTIONS?