Airdropped cash in bags? Or a hawala network with Russian businessmen who want to get USD? I would say crypto certainly simplifies the operation considerably, but it is not strictly necessary.
It's tougher to get US business executives to sign off on paying with cash in bags due to the higher risk of criminal prosecution. That might have worked back when the casinos were mafia run but now most of them are publicly traded corporations subject to strict oversight.
There is generally no criminal prosecution for paying ransoms. There might be if the ransomware group is sanctioned but that would true regardless of payment method. If a public company paid a ransom via cash or by buying a bunch of bitcoin through an exchange they would still have to make the same 8-K filings and accounting changes etc.
Correct. The "Nigerian Prince" scam existed before email, but that doesn't mean we should eschew spam filters.