But then the argument is: why would I turn it into usable cash if everyone used it. And by the time you reach that point in the discussion, back slowly away...

the only identifiers i can think of are my height, gait, voice and clothing. Though i get your point and it does seem to be getting harder and harder to find local dealers willing to transact without seeing photo ID. I still think it can be much more private than cash-only purchases, depending on how careful you are about it