They are not bugs, they are backdoors introduced on purpose. No one is forgetting how to close them, its on purpose.

To reach that conclusion for all of them, that none of these are bugs, you must think the legislature is much smarter than I think they are.

We can't write bug-free software even with unit tests and formal methods, what hope does a legislative body have? Debate before a law passes may be like code-review (and for big bills this debate is essentially "LGTM"), but most-to-all of the testing is in production: https://en.wikipedia.org/wiki/Test_case_(law)

This is not to say that no deliberate tax doges, they certainly do exist, but there's a lot of bugs too.

I think that we are not really far from time, when law text will need to be formally verified to either prevent these kind of loop holes or at least point them out.

Don't we have a separate name for intentional bugs? I mean it's not like tax loopholes are there accidentally. They are fully, 100%, intentional features of the tax code.

Some are, some aren't.

You can tell the ones which aren't by watching them getting removed in a hurry when the government finally notices too many people using them. 10-15 years back, some colleagues had made businesses for themselves just so they could receive their real jobs' income at the lower rate of dividend income rather than the income tax rate. I am told this is no longer possible.

Conversely there is (or was) what I think was a deliberate loophole for UK inheritance tax — if I remember right (not a lawyer) it works like this: physical objects in your home are all bundled together and valued at £1 for inheritance tax purposes, so fancy art, stamp collections, etc. don't get taxed.

We have a name -- it's called "backdoors"

Why not be maximally moral and donate all your money to the government?

Maximum morality isn't that simple for many of the same reasons that it isn't as simple as "if you can exploit the loophole it must be fine".

Government bugs aren't limited to the tax office.