At the same time, there are numerous historical examples of non-violent non-compliance nullifying that power. For example, when the Danish just refused to help the Nazis to isolate, persecute and exterminate Jews in their country, the Nazis weren't actually able to do all that much to change that.

People at Apple just refusing to assist the government is, in a way, the government's worst nightmare: it shows just how little power they actually have.

Some weak forms of political power grow out of the barrel of a gun. True power grows from the consent and support of the governed. Withdraw that consent, and the gun is shown to be a pitifully ineffective tool of government. Maybe this is a historical lesson we need to re-learn.

Or to put it another way:

"You don't really own anything that you couldn't carry at a dead sprint while firing an AK-47 over your shoulder."

I dunno, it seems a bit like saying the dollar has value because of the gold in Fort Knox. Possibly it was once true, and it provides a pleasing sense of solidity to an intangible thing, but the scary reality is that it's largely down to social convention. If enough people rejected the legitimacy of government wholesale, its power would evaporate and brute force would not restore it.

As Max Weber would say, the government has a monopoly on the legitimate use of physical violence.

That's not a very insightful definition because it pushes the question to what is "legitimate".

Some governments may claim such a monopoly, but in the most parts of the USA, at least, private citizens have not completely delegated their right of self-defence through physical violence.