Just some examples:

https://en.wikipedia.org/wiki/Corralito

https://en.wikipedia.org/wiki/Argentine_currency_controls_(2...

https://www.statista.com/statistics/316750/inflation-rate-in...

https://hongkongfp.com/2023/12/15/hong-kong-govt-amends-nati...

https://www.ibanet.org/article/5584f623-6456-4287-8c34-1907b...

https://edition.cnn.com/2022/02/20/americas/canada-trucker-p...

How are these solved by cryptocurrencies?

In the case of Argentina, in most cases people have turned to the much safer USD.

Only when and where they've been allowed to.

How would they be allowed to switch to BTC (or another decentralized cryptocurrency) at a greater rate than they're currently allowed to switch to USD? I'd imagine it wouldn't be much harder to crack down on one than the other, given that the USD is also predominantly a digital currency.

Capital controls are becoming more and more erratic and authoritarian. A decentralized currency provides a relief valve.

More erratic and authoritarian compared to what time?

As recently as 1989, most of the world's currencies were tightly controlled and exchange rates were fixed. In many countries like the Soviet Union, you were not even allowed to bring local cash outside of the country at risk of high penalties. Sending an international wire transfer was a multi-day operation that probably involved telex messages and several phone calls.

Today you can send money instantly across the European continent in a single currency at essentially zero cost. The USA is also catching up and finally bringing their banks to the 21st century with Fedwire. Everybody has multiple credit cards and uses them for online shopping across the world. Any physical product you might imagine can be ordered from China with a one-click digital payment.

None of these improvements were thanks to Bitcoin or any other cryptocurrency.