I suggest two simple solutions would work. First, we must have automatic information exchange of data on who has an interest in a bank account in a tax haven. We don't even need to know the income earned, just that someone has an interest in a bank, in a bank account, or some other structure in a tax haven. That's the smoking gun that will let your tax authority pursue the tax evader.
Second, we must have mandatory disclosure of the ownership of all companies and trusts on public record worldwide, in developed countries, in developing countries, and in tax havens. That's the minimum price of using these structures.
Do those two things and you will not solve all tax evasion, I readily admit, but I guarantee you will substantially increase your tax yield, and if that's what you want to do, I strongly recommend those two courses of action.