Thank you for the explanation. Perhaps I wasn't entirely clear - I wasn't suggesting opting out of RBF made double spending impossible, just that the transaction couldn't be redirected to another address using RBF.
businesses accepting zero confirmations are straight up reckless!
I'm not sure I would agree with that statement. More or less every company in the world accepts credit card, which can have payments reversed for weeks or even months after they are made by me claiming my card was lost, stolen, cloned, I was defrauded, I was overcharged, etc. A company like Starbucks can quite easily eat the price of the odd coffee here or there from a double spend attack. Sure, if you are a small business, or transacting with significant amounts of money, wait for some confirmations, but $3 to Starbucks is completely negligible. Alternatively use LN.
