Government can charge a fee for bearer assets

In sandbox, the definition of cash is no double spending.  Beyond that currency and contract issuers have no restrictions I can think of, except fair traded pits.

So, for a $50 cash limit in our hand, we give it a sales tax, even, a monopsony fee. No problemo.  Thus government can collect a fee for endogenous internet purchases (internet goods only, like trade journal article).  Secure ID can obey rules much like a regulated bank, backed by counterfeit technologies. It has active contract management. 

Central banks have competition, sorry about that. Dollar derivatives are easy to generate, just down load the standard pit and open it for trading. So, government has to obey the known rules about price fixing, what works and what doesn't. Sandbox is an unbiased distribution of technology.