GNU Taler is an anonymous digital cash, but it’s not yet widely adopted, I think only a few banks in Switzerland are using it. Hopefully if continues to gain momentum.

Cash is the correct option.

The person raising alarms about note scanning is misinformed about how frequently atms actually scan bills as they go out (it may be that all British atms have been updated in the last ten years but it’s not likely) and has completely discounted the laundering effect of just buying something small with your big bill or getting change at a store somewhere.

The argument against cash is that they know what bill you took out and that they know where that bill got deposited from, because the atm reads the bill serial and the bank does too when the shop makes their deposit. So they know where you went!

Even if you can only pull from an atm that scans the bill serial and you have a bank that actively correlates that information to your kyc account holder information and uses facial recognition to verify it’s you using the atm taking physical custody of the withdrawl, when you use a 50 or a 20 to buy a bag of potato chips or ask a bar to change your 100, the cash you get back isn’t now associated with you.

Further: places that deal with cash do not deposit every bill they take in, so there’s a decent chance that the panopticon will never associate your withdrawal with having gone to the corner store or the bar sometime after you withdrew the money. Those bills may have ended up making change for someone else or in the cash portion of the tip out or used to cover some expense that day or any number of other things.

So the choice is between some electronic form of payment where there’s an absolute paper trail between you and the recipient of your money, with a transaction id that can be correlated to your purchase.

Or

The possibility that the atm read the serial number of the bills dispensed to you, then if they made it into some shops daily deposit, the indication that that bill was possibly spent at that shop.

No indication it was you, no paper trail, no transaction id, no amount of purchase that can be correlated with actual items based on their price, just two data points with no real correlation between them.

Use cash.

Monero

Coincards allows you to buy gift cards with crypto.

Cash isn’t private due to banknote serial scanning. Now we need a remixing service for physical cash.

For cryptocurrencies, look at Monero.

Cash is pretty accessible where I live, but I’m always in for a surprise when I gravitate towards self-checkout and realize that it’s a card-only machine.

Prepaid cards used to be my go-to online, but it seems that fewer and fewer payment processors are letting them through their “security” checks. They were also next to impossible to obtain when I was in Europe. For a lack of better options on hand, I went with privacy.com’s virtual cards, which doesn’t really anonymize things in the eyes of MasterCard, but I suppose it’s better than nothing.

The only other thing I could think of is signing up for eBay or Amazon with a pseudonym, paying with gift cards purchased at a store with cash, and shipping to a PO box or Amazon pick-up location.

Ideally Monero, but it’s not as straightforward to obtain and there’s a very limited selection of vendors that accept it.

I use prepaid cards for Twitch and similar online services. It’s great because they always try to dark-pattern you into subscriptions, but then they’re all plaintive when your account runs out and they don’t have a credit card to perpetually drain. (actually, it’s more like “stages of grief”… first it’s alarmist: “your payment has failed!!!” then it’s businesslike: “remember to re-subscribe!” THEN it’s plaintive: “(name of performer) misses you on Our Moneydraining Platform!” then it’s nostalgic: “remember the good times you had on Our Moneydraining Platform? It’s not too late to re-subscribe!”) However, there’s usually a slight extra charge for the cards.

Cash irl is great but a slight downside is making sure you’re always carrying enough. Also, if you drop it somewhere it’s just gone.

privacy com

Prepaid credit card? Although I’m not sure to which extent it’s really private. Usually the type of ‘voucher’-like payment options are kinda sketchy.

I think you’re pretty much limited to the kind of options the seller accepts and they are usually not the type of options to value privacy.

IME crypto is largely useless as a means of payment, not just in the real world but also online. Literally nothing I have ever bought online could be paid with crypto, no stores that sell useful tangible things takes them, be it hardware (kitchen, computer, whatever…), groceries, things for hobby projects. There’s just nowhere to spend it.