OK...

I would be more credulous if you could show a path from me, say, working for someone to me, say buying something at a store and show that I couldn't say, buying two of that something by doing two different anonymous transactions.

- My argument is that the factor prevents me from using my information twice is the factor that identifies me (how does X know that "coin" Y belongs to Z? - The audit trail - if the audit trail can't show this, the whole app break. If the audit trail does show this, the state can figure things out).

Once I'm identified by other bitcoin participants, I'm identified by everyone and so the state will say "hey, you're transacting, you owe taxes"...