Who cares how cash was intended to be like 100 years ago, it rationally bears no relevance to how it should be done today. I said they
are not supposed to be private, not that they
weren't.
The IRS sets a cash threshold above which you are required to manually report the personal information of the payer (ie Form 8300). The headline notes the Israeli threshold at 6000 shekels, the IRS sets it at 10000 dollars. We've established the threshold, we're just haggling over the number.
I never expressed any intention to allow people to hide from the government based on technical hacks that won't realistically be known or used by most people anyway. If you don't want government to read your stuff, that's the law's/legislature's job to determine that, like the Stored Communications Act. While criminals and citizens alike have equal access to technical loopholes, the law alone distinguishes between them.
Financial crime is the backbone of organized crime, it is the foundation of hostile spycraft and funds the most depraved regimes. I absolutely refuse to regress to the era where the mafia and cartel leaders ruled the streets and stood toe to toe with law enforcement. Anti-laundering laws are written in blood and they are designed to prevent those scenarios, not tie law enforcement hands then blame them for not working hard enough. You're going to have to do more than spout libertarian cliches to convince anyone.