Milhouse: I don’t believe you to be correct regarding your points vis-a-vis dina d’malchusa taking preeminence and overriding how Halacha rules monetary disputes and situations are to be resolved. See Choshen Mishpat 26:1. And minhag hatagorim I believe applies to parties who participated in an agreed transaction; not to every monetary issue or dispute such as, for example, someone damaging property of someone else who he has no financial or business relationship with.
What you seem to be suggesting is that we can basically throw out Choshen Mishpat, lock stock and barrel, and simply always use the lawbooks of the local gentile state with never a need for what Choshen Mishpat rules on given scenarios.
I’m also not convinced you can extrapolate from a tzibbur to a corporation, even if they bear some similarities.