Some charts are created using public funds. It would seem reasonable to make them public property but, unfortunately, the revenue from their sale is needed to pay for the work of updating them. Electronic charts companies must, one imagines, pay some sort of royalty. Anyone, as far as I know, can exchange paper charts, since no revenue is lost in this manner. You have mine and I have yours but neither of us has anything we haven't paid for. Most software companies make it very clear in what manner their wares may be shared, if at all. It might be worth posting again under 'Do electronic chart exchanges exist, somewhat like napster's music exchanges?' and see if that brings a knowledgeable reply. Good luck!