Regardless, both cases show that it's pretty hard to actually get caught doing it.
(a) is not a crime by itself, but it raises red flags, and there usually needs to be a really good paper record showing, for example, that other options weren't available, and that only market prices were paid. (b) is basically misappropriation or embezzlement, but depending on the amounts involved, it can be considered a mistake and healed by paying it back. Not sure about (c) and (d)'s legality.
There is absolutely nothing wrong with structure of, for example, the Bill and Melinda Gates foundation, or Soros' Open Society Foundation. Yes, the foundations are not subject to inheritance taxes. But the money is required to be spent on altruistic endeavours. It cannot be clawed back for personal expenses, not by the founders, nor by their descendants.