Now I'm confused. Bitcoin is not lighter weight than existing digital cash. It's not really lighter weight than anything. Well, possibly the large hadron collider consumes more, I don't know.

There is no such thing as digital cash outside of cryptocurrencies.

The money in your bank account is a liability of the bank, it's not cash.

You can go through life without ever using physical cash. You get paid digitally, you buy groceries digitally. You even borrow money for a house digitally.

The thing you transact with is digital, liquid and fungible. In what sense is it not cash?

All those transactions are reversible at any point with a flip of a bit (or two).

If you receive physical cash, it's in your control.

Now if only that cash could not be inflated as much as it can.

I don’t think any common definition of cash includes the idea that payments are “irreversible”. I don’t even see why this is so important. If someone pays me physical cash by mistake they have legal recourse to get it back. It’s not finder’s keepers.

> Banks could issue digital cash with greater anonymity

Why would (a) my bank want to do this, and (b) why would I want my bank to do this?

The point here is that bitcoin is incredibly transparent, which on one level one may welcome, but on another certainly not.

(a) providing cash level privacy to customers, which (b) they should probably value more than they do.

What "cash level privacy"? Banks have to report all significant cash transactions and ensure that customers can't deal large quantities of cash anonymously; and in the exact same manner they would also have to report all significant e-cash transactions and ensure that every customer with whom they deal large quantities of e-cash can't be anonymous.

just post all your financial statements on the web for everyone to see.

you've got nothing to hide, right?