The 1965 Coinage acts says ...
“United States coins and currency (including Federal reserve notes and circulating notes of Federal reserve banks and national banks) are legal tender for all debts, public charges, taxes, and dues.”
And the definition of legal tender is “coins or banknotes that must be accepted if offered in payment of a debt.”
But, as you say, it is a lie. This place has really gone to hell in the last 60 years. lOL
It isn’t a lie. You are just having trouble understanding the term “debt.” A sale of goods and services is not a “debt,” a “public charge,” a “tax,” or a “due.” Every court that has considered the matter has held that the legal tender statute only applies to pre-existing debts, and that there is no federal statute mandating that a private business, person, or organization must accept legal tender as payment for goods or services.
If you owe me money and you tender cash to pay that debt, then the debt is discharged under federal law because the cash is legal tender. But if you want to buy a cup of coffee from me and offer me cash, I do not have to agree to sell it to you if I want you to pay with a credit card instead.