For example you could go there, buy a watch worth 100000 USD with Bitcoin, come back and resell it.
Enabling ransomware criminals, you mean.
But I still find it hard to believe that would bring the Panamanian or Salvadorian jeweler any benefit, let alone the rest of the population. The problem of converting the BTC rests with them after the purchase.
think of the power the US government has to freeze the funds of russian oligarchs - blockchain allows at least a version of this: not to freeze the funds, but to prohibit sending or receiving funds from a certain address
vendors could happily subscribe to this blacklist to ensure legal compliance (an RSS feed will do but thats just me)
For starters, download bluewallet and get some free sats to play around with:
https://fixedfloat.com/lightning-faucet
Quite a rabbit hole you're falling into. And no, there's no public ledger.
But maybe looking at what's in it for the government from the POV of the country's financial stability is the wrong question anyway... one might also want to look at the personal financial stakes of some of the individuals involved...
But better: now the authorities can instantly see all financial transactions? Using their special app (El Salvador) which connects each ID to a BTC address makes it possible to know exactly who is doing what and where. Yes BTC can be used to pay taxes. But much more important they can now probably see much better how much taxes should be paid in the first place. This might schrink the dirty money part of the economy immensly.
Seems like good reasons to me, short term the first two are probably the important part, longer term the last one could be massive for countries struggling with massive corruption. Like any good idea it can be subverted or corrupted though so let's see.
In El Salvador, they avoid up to $400 million in bank transfer fees when citizens working in other countries send their earnings back to their families.