There are still a few countries with wealth taxes[0]. I'm not sure if they work well or not for these countries. Picketty doesn't spend to much time on the subject of existing wealth taxes. He is more focused on a global wealth tax, which is much more ambitious. Something that would need to be designed for the digital era indeed.
Amusing find from the linked article: Back in 1999 Trump proposed a one time wealth tax of 14.25% for individuals worth more than 10 million.
Amusing find from the linked article: Back in 1999 Trump proposed a one time wealth tax of 14.25% for individuals worth more than 10 million.
[0] https://en.wikipedia.org/wiki/Wealth_tax