If your money is in a shell that you cannot reach/touch, do you really have it?
And if you can't, why is it on the balance sheet as if it were cash that you could reach?
And the same companies stuff all the non-US revenue into a low-tax subsidiary, even when it's effectively earned in high-tax ex-US jurisdictions to avoid their taxes too.
That's exactly the problem! These are extremely complex situations where there usually doesn't exist any clear answer. If there did, large corporations almost certainly would not take these steps.
If there were clear laws, then taking these steps could be criminal tax fraud. Blame the regulators.
There's nothing stopping nations from writing clearer tax laws.
I don't know, but I also doubt that anyone else really knows.
I can't even imagine a moral obligation to pay excess taxes, that's simply not how taxes work.