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.