It's almost like they never took physics.
I'm sure they do understand the physics, but (as with many other things in this game) they simplified it a bit for the sake of easier programming.
Doing what Dinjack suggests would be a pretty big programming task. They'd have to reprogram the game so that when you begin your round, the prevailing wind speed and direction is calculated and the course layout is taken into consideration for each hole. It's a whole lot easier programming-wise to just randomize the wind for each hole.