> Wouldn’t that just cause a massive amount of confusion over what was legal cash and what exchange rates are?
In practice, this has never been a problem, when it was tried historically.
What typically happens is that the different vendors standardize on a common unit of account (eg Pound Sterling in Scotland or Canadian Dollars in Canada, both of which were defined as a particular amount of some precious metals).
Typically issuers will redeem not only their own notes, but also accept other vendors notes at par---as long as that vendor is known to be solvent.
(The US was an exception to the latter, owing to their widespread bans on banks having more than a single office.)
The situation was pretty similar to how bank accounts still work today: if you have a dollar in an account at bank A, bank B will typically accept a transfer at par.
If someone is trying to pay you, you only need to know whether your own bank accepts the notes in question (or respectively whether your own bank accepts a wire transfer from their bank).
> One of the economic strengths of the US is its unified currency which has been poorly copied by the euro.
That was also a global strength during the gold standard. Common acceptance at par is enough for this. It's not necessary for everyone to use the same brand of currency.
George Selgin's book 'Good Money' is especially interesting. It's about Britain during the Industrial Revolution when the Royal Mint refused to mint enough small coins for factory owners to pay their staff. So some factory owners made their own coins (redeemable in demand into Pound Sterling).
In practice, this has never been a problem, when it was tried historically.
What typically happens is that the different vendors standardize on a common unit of account (eg Pound Sterling in Scotland or Canadian Dollars in Canada, both of which were defined as a particular amount of some precious metals).
Typically issuers will redeem not only their own notes, but also accept other vendors notes at par---as long as that vendor is known to be solvent.
(The US was an exception to the latter, owing to their widespread bans on banks having more than a single office.)
The situation was pretty similar to how bank accounts still work today: if you have a dollar in an account at bank A, bank B will typically accept a transfer at par.
If someone is trying to pay you, you only need to know whether your own bank accepts the notes in question (or respectively whether your own bank accepts a wire transfer from their bank).
> One of the economic strengths of the US is its unified currency which has been poorly copied by the euro.
That was also a global strength during the gold standard. Common acceptance at par is enough for this. It's not necessary for everyone to use the same brand of currency.
See eg https://oll.libertyfund.org/title/white-the-theory-of-free-b... and https://www.cato.org/blog/what-you-should-know-about-free-ba...
George Selgin's book 'Good Money' is especially interesting. It's about Britain during the Industrial Revolution when the Royal Mint refused to mint enough small coins for factory owners to pay their staff. So some factory owners made their own coins (redeemable in demand into Pound Sterling).