Generalizations like "acts/used/properties like a currency" can apply to any commodity. What does not apply to any commodity are the things that make a currency a Currency. Per the Australian legal system, that'd be something tangible backing it. Per most legal definitions I've come across, (synonym: banknote) that'd be a government's central bank.
It is up to each country. In the US, FinCEN laid their rational on how the regs that give them oversight over monetary value cover Bitcoin. Now you can disagree but simply not calling Bitcoin a currency doesn't really have any merit.
If the state believes your activity is regulated (regardless of if you call Bitcoin "virtual carrots") you can:
a) ignore them and hope you can avoid legal action
b) ignore them and intentionally try to cause legal action to force a precedent
c) bypass them (write off the united state and focus on non-US clients)
d) comply
My point it ultimately what matters is what the STATE (each state independently) defines Bitcoin as. You can call them anything you want but FinCEN (and other states) is regulated based on what Bitcoin DOES not what you NAME it.
TL/DR: If Bitcoin is used "as monetary value", FinCEN intends to regulate it, regardless of what you call it. Their authority (or lack thereof) comes from what Bitcoin DOES not what it is CALLED.