This seems backwards to me. Labour can leave; someone can get on a plane in the UK where they get taxed 40%, and arrive in Dubai where they're taxed 0. Their buildings and assets can't come with them however. Capital that's not ethereal assets like stocks, shares, credit, etc, can't be moved. If you want to leave the country you need to become liquid, which means you sell off your assets and whoever is left in the country gets to buy them at cheaper rates.

The issue is when we allow people who do not live or pay tax in this country to make profit on assets in said country. A landlord who lives in the Cayman Islands should not be able to collect rent on UK assets while not paying the UK government tax in turn.