Stand on the left side of your bicycle facing forward with your hands above the bars, now rotate your upper torso to the right 90 degrees. Your right hand will be over the rear derailer and rear brake, your left hand will be over the front derailer and closest to the front brake. Now rotate your torso back and your left hand will be over the front brake lever and front derailer shifter, your right hand will be over the rear brake lever and rear derailer shifter. Show this to a newbie and they will grasp (pun not intended) the concept of which lever does what instantly. So, maybe that is why they are laid out that way.