Taxing wealth suffers from the same problem. People who have a lot of wealth will move that wealth to places with the lowest tax burden.
Basically, the truly wealthy will start living in luxury apartments while shuttling their wealth to the Costa Rican villa in which they are planning to reside during retirement.
That relies again on making exceptions for wealth held outside of the country. Not providing these exceptions and just making it flat wealth no matter were it resides fixes this problem too.
No, it doesn't fix the problem and it creates several others. That's the biggest problem with all of these quick-fix new tax ideas, the proponents never think them through.
1. What jurisdiction does one country have to tax assets held in another country?
2. Why wouldn't the country where the assets are located be the one to tax them?
3. How would you address the possibility of double-taxation?
4. How would you prevent the wealthy from shifting ownership of these assets to corporations or family trusts that are incorporated in that foreign country. Assets located in a foreign country, owned by an entity in the country would be taxed in that country.
We should tax wealth instead.
By not taxing income you avoid placing the burden on those that don't have and thus avoid needing to create loopholes for them.