That's because it effectively is. I suggest you look into pledged asset lines (and more broadly 'buy, borrow, die'), which are even more tax advantaged than just getting paid directly. Sure, there is some marginal cost associated with borrowing against granted equity, but it's almost certainly less than 10%. So yes, it is accurate to assume that if an exec vets $x00 million dollars of equity a year, they have a high percentage of that available to spend on whatever consumption or investment they desire.
Quite possibly the best comment in this thread. Some people are quick to say that the high on-paper number doesn't mean anything, but remain (in most cases wilfully) blind to the fact that the low on-paper number doesn't mean anything either. As you point out, the real number is unknown and often not fixed but for all practical purposes probably still way higher than most of us will ever experience.
