This is interesting news indeed. Buying with cash is fine, but buying with cryptos could be more useful and still guarantee privacy. I find it weird that legal marijuana purchases are being investigated and can become a reason to deny entrance to the US, though. I mean, it's not like US is some super strict country that banned weed... And information about purchases of anything via debit cards should not be available to third parties.
Without being biased, fiat still remains the most convenient way of doing transactions (for now) but on the other hand, it doesn't mean that crypto got no future at all. Actually, if I really had a chance to buy goods with my btc then I would love to not mainly because of its anonymity, cashless transaction etc. but because I believe in its potentials and I want to give contribution to its adoption.
I don't know why you find cash convenient. When you move to another country, you need new fiat; those goddamn coins in the pockets; cash is very vulnerable and can be easily spoiled; cash can be fake; you have to count what you give and what you get. Debit cards are much easier, and if I could use a crypto card, I would.