Any currency worth using may be used for ransom. If currency can't be used for ransom, it's not anonymous enough and should be avoided. So existence of ransomware is the best marketing for cryptocurrencies. Just like terrorists using E2E messengers are the best marketing for encrypted messaging. If some people (does not matter, whether they're evil or good, just not stupid) are trusting technology with their freedom and lives, this technology is worth looking at.

> If some people (does not matter, whether they're evil or good, just not stupid) are trusting technology with their freedom and lives, this technology is worth looking at.

Yes, criminals would be stupid if they didn't use this technology. The concept is a gift from heaven for these people.

What we need is a currency that is anonymous except for the two parties involved in the transaction, i.e. similar to cash but without the downsides of cash.

Possibly GNU Taler? https://taler.net/en/features.html

However, I don't know enough about this system to know if this is what you're looking for.

Interesting but this usecase doesn't seem to be specifically addressed.

I agree. In the end it’s all fiat currency anyway. What does any currency have without the rule of law?