I would say that luck in FAANG interviews is much lower than the average tech company. At least in my experience. Don't get me wrong, there is luck involved, and it's a big part of the interview process.

But, at least, you have standardised pools of coding questions, standardised pools of system design questions, and a standardised feedback form.

The interviewer varies a lot though... And makes all the difference when you have an inexperienced one, or someone that doesn't care.