Not every established common practice implies a contract to follow that practice. It also matters what the reason for that practice is, and whom it's even relev

Not every established common practice implies a contract to follow that practice. It also matters what the reason for that practice is, and whom it's even relevant to. Like just because most people take the highway when driving from SF to LA that doesn't mean you're breaching some sort of contract by opting to take a side road. There are two practices here. One is passing the program name to arg0. The other is never making some use of arg0. Both of these are established because they're the most convenient things to do by default, and because people rarely have a reason to deviate from them. That's it. Heck, if there was some contract to ignore arg0 then people wouldn't feel any contractual obligation to pass the program name to begin with, since it should be getting ignored anyway - that argument is pretty self defeating. Moreover, I think your position is effectively equivalent to saying "if you don't want a common practice to become a contract, then you must go out of your way and inconvenience yourself to deviate from that practice for absolutely no other reason than to make this very statement true", which is a rather bizarre (and inefficient) expectation from everyone around you.