> When “doing crime”, I’m really not interested in committing the transaction to a permanent public ledger.
As the recipient of the funds you need everyone else to agree that the funds are actually under your control. That requires a public ledger associating unspent funds with access credentials. The payer needs the same thing so that the recipient will accept the payment. ("Permanent" goes without saying; even if old transactions can be pruned from the database there is nothing to prevent someone from keeping a copy of the full history.)
What you want to avoid is having your real-world identity associated with the funds, which is where privacy-focused coins like Monero come in.
Even if you handle payments offline with briefcases full of unmarked bills you're still leaving a trace an investigator could follow, possibly even more easily than they could follow a trail of transactions through a suitably resilient cryptocurrency.
As the recipient of the funds you need everyone else to agree that the funds are actually under your control. That requires a public ledger associating unspent funds with access credentials. The payer needs the same thing so that the recipient will accept the payment. ("Permanent" goes without saying; even if old transactions can be pruned from the database there is nothing to prevent someone from keeping a copy of the full history.)
What you want to avoid is having your real-world identity associated with the funds, which is where privacy-focused coins like Monero come in.
Even if you handle payments offline with briefcases full of unmarked bills you're still leaving a trace an investigator could follow, possibly even more easily than they could follow a trail of transactions through a suitably resilient cryptocurrency.