Sure, those things happend, but a vet or an experienced crew would not leave an "untouched" Tank. Not to mention, that you get shot by your own Men for deserting.
I mean, what can be saver on a Battlefield like a Tank?? If you bail out, you are then not only a Traget for the ennemy Tank, no, you are then also a Target for anything that can shot at you, including Arty. And the terrain around a Tank is mostly open and not the best to give you cover.
I say, if the Tank is able to move, no one would leave him without a emergency situation.