What if an employer paid you in coins, so you take your coins and go home, then tomorrow your employer decides to take back the coins they gave you since they were not happy with your work (or they're just jerks)? I think that would fit the layman understanding of "this was undone!" (i.e. the transaction wasn't final). If in this case, the underlying financial engines used two, none, or one transaction (as specifically defined by that engine), probably wouldn't matter to the one who no longer has their coins.
The government is certainly a different party that wasn't involved in the original transaction, right?
> What if an employer paid you in coins, so you take your coins and go home, then tomorrow your employer decides to take back the coins they gave you since they were not happy with your work (or they're just jerks)?
This can definitely happen, at least with checking accounts. It has happened to me once because an employer accidentally double-paid everyone, and they were able to withdraw one of the payments from our accounts. I'm not sure exactly how that works. It could just be that your employer essentially has full access to your checking account since you gave them your account and routing number. Incidentally, I was always curious what would have happened if I had moved everything out of my checking account before they make the correction. But regardless of how it is actually implemented in the banking system, it's pretty clear if your employer erroneously removed funds from your bank account, or if you cashed out the accidental second payment then quit your job, it would again just come down to the legal system.
But to the entity who received the coins, it also doesn't matter where the coins went after someone took them by force. If you get paid for a day's work in cash and a robber steals it on your way home, you wouldn't say that your work payment transaction was reversed or that it hadn't been finalized up to the point of the robbery.