Commerce is legal jargon which doesn't carry the same meaning as regular English. You're misinterpreting it because you're not treating it in its legal context.
There is no magical legal context. What you're referring to is people being dishonest and trying to cheat and get away with violating the constitution by pretending words mean different things. For instance, the power to "regulate" is not the power to ban, though politicians and judges have pretended it is, and many people have been tricked into believing it.
