I think it's more like asking "Should Mr Y have been ticketed for reckless driving" if it's on a backcountry road without cops or speed limit signs. Not getting audited doesn't mean it was ethical.

I'm comfortable saying a tax loophole should be banned without saying it's users are criminals or either unethical. Asking if someone should be able to deduct their private jet is a political question to me, not a legal one.

But there are other instance where people are taking advantage of lack of enforcement. For instance conservation easements. There's an example of a mining developer who gave 6000 acres to a charitable trust in CA. An issue is the mining company didn't own the subsurface gas and mineral rights to the land. They weren't explicitly clear about that when donating, so the donation was probably overvalued.

https://www.kassounilaw.com/publications/the-uses-and-abuses...