It's always kind of bugged me this has never been addressed in the comics:
Superman has always been a victim of "power creep". He started out with abilities that at least conceivably could be explained as the result of being born on a high-gravity world. Then stuff kept getting added, to the point where one time in the Fifties he actually blew out a sun with his super breath.

Okay, forget for the moment that that's scientifically ridiculous. Posit that all retentive/expulsive features of Kryptonian physiology must be similarly impressive. Forget snow, he could write his name in the bedrock! And, my God, people, what if he farts in his sleep?? Yeah, convince me Batman's got a contingency plan in place for that.

(One wonders what Ma and Pa had to tell the Smallville plumber while they were potty-training Clark.)