That was the default in the UK for quite a while and a lot of (typically older, I think) people still use a physical card for contactless payment. Most people have moved to mobile contactless payment because it’s just as quick as fishing a card out of a wallet, most people always carry their phone and it has a degree of biometric security that the physical card doesn’t. I don’t generally carry a wallet or cash and haven’t for years. I have all my cards in my e-wallet, including my default credit, bank, loyalty and even my work door access cards on there. If I do forget my phone, I can do all their same from my watch and never have to carry a wallet with a dozen pieces of plastic in. A win for pocket space, if nothing else!

I think that’s a Thiel thing. Tolkein was was one of his obsessions growing up. It doesn’t surprise me that he saw a plot device intended to be a warning as a really cool idea…

That sounds like an XOR pointer, which did used to be a standard feature in Windows. There were patents on it and xorg were threatened with legal action by the patent holder, so I don’t think it was ever added to X. Those patents have probably expired now, so it may be possible to do.