Scott Duncan
So if taxi offers a ride you can presume it's "free", and give a "notice of mistake" in leu of payment? Do you really think that?
Well you didn't make the money either, and it is FIAT currency (which is clear on the note) so SOMEBODY who is NOT YOU is PAYING to create this BENEFIT.
If you use MONEY, you are already bound by the very tender you accepted by using the money.
You don't get to go "my mistake" after.