I noticed that too, but I agree. Superman is invincible with a weakness to a rock that seems to be rather easy to find (because villains keep finding it). Superman often gets caught, and it takes a woman to save him (i.e. Superman The Movie and Superman Returns). Batman is mortal, but he still always comes out on top, often using his own determination, abilities, and gadgets. Batman just needs to use Kriptonite and make sure women don't get in his way. =^)