"Taxation: How do governments collect taxes on transactions in Bitcoin? The answer is they don't, and they can't."

Grossly misleading.

You tax something at the point at which it gets exchanged into an externally viewable good or service. If either party refuses to disclose the value of the transaction, then the state just assigns one and uses its monopoly on force to collect.

That said, an increasing dependence on opaque stores of value would likely shift taxation away from income and towards consumption.