I guess here we get into the discussion of “what is income?” and “when is the income realized - made real?”
Most stock options are future-dated(? is that the expression?) because if not, why not just give you the stock at fair market value now. The idea is you get a certificate to buy X shares at $Y on the theory that if, in part thanks to your titanic effort, the stock goes up instead of hitting an iceberg, you will make an immediate profit - sometime in the future.
I assume that most such options are not tradable. The person being rewarded must specifically redeem them. Otherwise, they are simply futures options. (Plus, there are other requirements, like “still employed by the company”. You hear of situations where someone is conveniently let go just before their options vest.) Do they typically expire too?
So essentially, these things are worthless until they are redeemed. Therefore, logically, on day X-1 you own nothing, on day X you own Y shares worth $Z, thanks to your employer’s generosity. You only paid N for them, the rest is cash in pocket - (Z-N). It’s income, you owe taxes. pretty logical to me. I assume there’s some clever accounting trick where it’s capital gains so you pay les taxes.