> I'd expect that each spam recipient is given a unique BTC address, so that they can be identified for further "blackmail"[0] should they actually comply.
They typically aren't, actually. Most of the time when you enter the wallet address into Blockchair or another BTC transaction monitoring service you'll see tons of payments for the demanded amount having been sent to that sole wallet.
Even thinking of it logistically, its a whole lot easier for a scammer to just send literally the same email to every victim, wait some months, then withdraw the funds from one BTC wallet.
It's such a simple scam, anyone who can make a BTC wallet and send emails could pull it off.
Fair points.
But if you use the same bitcoin address for every email, you won't know who the mark that actually paid was -- potentially leaving money on the table for the future.
I did (before posting the comment to which you replied) check to see if there was any activity[0] on the bitcoin address in the email I posted. There was none. Which strengthened my conclusion (I have no evidence) that unique bitcoin addresses were in use.
But I certainly could be wrong.
[0] https://www.blockchain.com/explorer/addresses/btc/bc1qt30ya4...