Hey Derek,
based on your reply I think you did not read carefully what I wrote.
If we both are still talking of the specific VFD mentioned above, it is crystal clear what the manual and the nameplate of this VFD say: 20 A @ 110 ±20% V 3-phase electrical output capacity. When you are an electrician, and you have a clear statement of the VFD manufacturer which gives you the specification of the ouput rating (and we have this here), I believe your duty would be to calculate the input circuit required, based on these data that are there. I believe you cannot say “Let’s ignore what the manufacturer wrote into the manual and on the nameplate, because it could be wrong”.
If you really mean what you say here, the conclusion must be that you would in any case refuse to connect the specific VFD mentioned above to any supply circuit. Okay, I would support that. Perhaps it’s better than what I say (which is to at least dimensionate a 45 A circuit, I still believe you would be on the safe side with that).
In my opinion, even if I never would recommend these cheap chinese VFDs, I would still think you can make a safe statement on the dimensionating of the input circuit, by taking the manual and nameplate statement on output power. If you have such a clear statement of the rated output of a VFD, and the input rating is missing, of course you can (and an electrician in my opinion should, at least it is desirable) calculate the approx. input rating (of course one would need some knowledge on how a VFD works).
I don’t know which 120 V 2.2 kW VFD could have a 22 A input power rating, you did not show this somewhere. I have seen this nowhere.
By the way, the “2.2 kW” rating of a spindle, according to IEC 60034-1, does not mean its electrical input power. And the VFDs manufacturer, when they call a VFD model a “2.2 kW” model, this always means “for a 2.2 kW motor”, and does not mean any electrical rating of the VFD, but the mechanical power at the spindle shaft of the motor for which it is suited. A “2.2 kW” VFD usually has a capacity of approx. 3.8 to 4.5 kVA. And that is not yet the VFD input power, just the capacity it can deliver to the motor.
I know what you mean, but here, this should not apply. You are not talking to someone here that simply believes to be right, as is widely found on the web. I can grab into my bookshelf next to me at any time and look up if I’m right. So of course we finally won’t disagree (at least not if I’m right with how I see you). 
PS: I see you will reply again, but I only woke up in the middle of the night to go the can, it’s 5:56 AM here … 