The problem is a fundamental disadvantage in available manpower. Billionaires employ literal armies worth of extremely well paid lawyers, accountants and other professionals continuously working on finding and exploiting loopholes involving multiple jurisdictions, whereas most of the public services sector is barely keeping up. (Yes I'm aware that especially at the federal scale, the ultra rich sometimes outright buy special tax breaks, but that's not the case we're talking about)
The solution would be to allow punishing breaking the intent of a law, but given how politicized even the justice system is these days, I'm not so sure if that's a good idea either.
If you could specify the intent in a way that could be adjudicated, why couldn’t you just write the law better in a different dimension? “This applies only up to $X M/yr” or whatever.
Having someone later come along and try to devine what the “true intent” was and levy punishments for behavior clearly allowed by the law but against an imputed intent sounds worse for society based on laws than the avoidance of some taxes via a poorly written law.
The solution would be to allow punishing breaking the intent of a law, but given how politicized even the justice system is these days, I'm not so sure if that's a good idea either.