Why is it that pitchers never catch pop ups? It always amuses me.
It's actually largely because they never catch pop ups. Kind of a catch-22, but the 4 infielders do it pretty much every game. Pitchers don't.
Another factor could also simply be that the pitcher's act of throwing the ball makes it much harder for them to track the ball compared to infielders.
Of course, the age-old argument is pitchers are paid to pitch, not field, so as long as it's playable for the infielders, the pitcher stays out of it.