Aren't Paraguay, Brazil and Argentina in the same trade union? I don't know the details of Mercosur but in the EU you can buy whatever you want in any other EU country and take it back home without the need for customs. Where is the black market part of that trade?

As for your trade example I would like to see the details of that. There are not a lot of vendors that accept crypto and those who do, use 3rd parties which then usually require some amount of KYC (even if it's is minimal). Combine that with how many vendors are actually able/willing to ship to the country in question and you are left with a very small set of online stores. Add shipping costs and custom fees that will eat in your margin. So yes in theory you can setup an import/export company empire in order to exchange your crypto into local currency but that is pretty much the definition of "not scaling".

My point is: if a country wants to make cryptocurrency useless they can totally do it.

I'm not aware of all the customs details in Mercosur but if it is like EU then I would just spend all crypto in Paraguay and then bring gold or whatever back through without customs on other side. Lots of commodities that are high density you can carry on your person and fit a decade of Argentina wages on your person in a single <$100 bus ride.

If you need to cross a border to fetch your hard currency (or equivalent amount of goods) then what is the value add of using crypto compared to, say, opening a bank account in Montevideo and making a bank transfer?

They have dollar-bill-sniffing dogs on the ferryboat to Montevideo, so being able to cross any border rather than one specific border is a pretty big win. But actually, lots of Venezuelan refugees right here in Argentina buy Bitcoin to send to their families back in Venezuela, or the families of other Venezuelan refugees who pay them, and all the black-market currency changers are trying to get into Bitcoin now. A lot of them are still confused about the difference between Bitcoin, Tether, and Binance, though.

I'm still kind of baffled here why Montevideo was brought up (not by you but above) on a thread regarding Paraguay. Montevideo is in Uruguay. The border between Paraguay and Argentina was used specifically because it is so porous and doesn't work well for sniffing dogs. Getting to Uruguay on the other hand would require a ferry or boat, or a swim. If I'm not mistaken.

You can get to Uruguay by bridges, too, but it takes a lot longer if you're coming from Buenos Aires or going to Montevideo, and you can't get there from Paraguay without crossing into Argentina or Brazil first. Montevideo was presumably brought up because Argentines bank in Uruguay, not Paraguay. Nobody banks in Paraguay.

I have availed my self of using a Paraguay bank. Seemed fine to me. I do not have a account there. They exchanged my USD for any peso I like just fine.

Is there a reason why no one banks in Paraguay? There is a dude standing by the bank with a shotgun waiting to blow the head off of any robber, I felt very safe there and their service was quite professional and honest. More so than the street exchangers. I wouldn't have hesitated to open an account there if I needed to.

The dude standing by the bank with a shotgun isn't going to accompany you even to your AirBnB, much less until you leave the country. He needs to be there to keep people from robbing the bank, but it's not his problem if someone follows you home from the bank and robs you there.

There may be other reasons. Here in Argentina 21 years ago the government confiscated all dollar-denominated bank deposits and replaced them 1-to-1 with pesos, which you weren't allowed to withdraw more than a few at a time, so you had to watch helplessly as your money lost 75% of its value overnight. If I had to guess which South American countries something like that would happen in next, I'd pick Venezuela, Bolivia, Paraguay, and Argentina again, in that order. But that's not because I have deep knowledge of Paraguayan politics, so I could be wrong.

I brought it up because it’s close to Buenos Aires and because I’m under the impression that Uruguay is a pretty well run place. I’m assuming there to already be a lot of connections, personal and trade, between the two metro areas. I’ve never been to either and anything beyond geography is guesswork on my part. Anyway, thanks for the clarifications :)

The presumption absolutely no one will trade you crypto in your own country and you can't just mail out or in cash somehow seems like a pretty steep one (particularly in Argentina where black market trade of USD and all array of other stuff is rampant); but you must surely see the different between having your cash stored in a private wallet vs a bank account with a country that quite likely has tax and other legal treaties with your own.

I can't imagine it would be a warm feeling for someone with tax liabilities in Argentina to have a white-market bank account in a friendly country nearby.

Also my girlfriend points out that possibly there's less financial surveillance in Paraguay, and if you travel to Uruguay everything is more expensive, whereas Paraguay is poor so everything is cheap. But still AFAIK nobody here banks in Paraguay because you get robbed there.