> even if cash is legal tender and they, by law, _have_ to accept cash

this is not true as it is not what "legal tender" means. Legal tender is something that the government must accept as payment, not private enterprise.

> Businesses don’t have to accept cash.[0]

> There is no federal statute mandating that a private business, a person, or an organization must accept currency or coins as payment for goods or services.[1]

[0]: https://www.accc.gov.au/consumers/buying-products-and-servic...

[1] https://www.federalreserve.gov/faqs/currency_12772.htm

That depends on the country. There are many countries (including my own) where any business must accept certain parts of the cash payment system (around here a taxi doesn't have to accept the highest-value bank note, but the rest cannot be refused). And shops, of course. That's why newspapers bother to write articles about it.

Note that legal tender does apply to private entities when it comes to paying debts, at least in the US. Creditors must accept legal tender, or give up claim to the debt.

It’s true that private businesses can set pretty much any payment terms they want for a transaction that hasn’t yet taken place. But the moment you move to a situation where you owe money, they do have to accept cash.

They don’t have to accept cash in advance. They do have to accept cash for debts, such as when you have already eaten the meal.

They have to accept cash, huh?

* Cash Payment Method Will No Longer Be Accepted A Notice by the Patent and Trademark Office on 10/03/2017*

https://www.federalregister.gov/documents/2017/10/03/2017-21...