Second, you'd have to give up substantial amounts of privacy (both related and unrelated to the banning of cash).

As an example, to make taxes automatic, you would have to annotate each electronic transaction with its taxable treatment.

If I buy a ticket on Delta to go on vacation, that has one tax treatment (no effect). If I buy that same ticket on Delta to go on a business trip, that has a different tax treatment. (Further, I would wager that telling airlines which scenario it is would not be helpful in terms of ticket pricing/terms.)

If I buy a sandwich on vacation vs that same sandwich on a business trip, different tax treatments...(and the business trip airline ticket even has a different tax treatment than the business trip sandwich).