[horsestaple]

Yes, if you convinced a lot of people to transact in cans of beans, you would be undermining the control of the government. Just look at countries that don't have a (viable) currency. They are using dollars or euros and are subject to a foreign powers monetary policy.

Also no country defines sovereignty through voluntary consent. Laws applies to you whether you agree or not.

[danuker]

Democracy, as opposed to oligarchy, is where the people are ultimately sovereign.

Sure, laws apply to the ones disagreeing, but in theory, the government serves the people, not rules it.

Central banks however, have a large amount of control over everyone's financial life, yet the signal from voting is only very dimly forwarded to this institution, and there are limited checks and balances governing it.