I recently broke my own code at an interview and was rewarded with complete nonsense. Never again.
The FAANGs practically (sometimes, actually) give you a study guide, at least. Lots of smaller places act like knowing anything more than the names and titles of the people you'll be talking to would be cheating or something. I'm not gonna burn half a day or more just to bomb a question about graph traversal I haven't brushed up on lately, and I'm not gonna study everything unless I'm shooting for FAANG. Tell me what to expect, a few days out, with decent detail, or I'm not interviewing. I don't need to know exact questions but "first thing in the morning we'll ask you to do something with very basic data structures, like one of [short list of possibilities], and it will be on a whiteboard".
Then if you tell me the day is packed with 6+ hours of whiteboard problems I know not to bother, because I'll definitely be tired AF and bombing them after hour 3 no matter how much I study, because I'm not built to literally perform in front of people for hours on end. It saves us both some time.
The study guide is hundreds (thousands?) of pages. How is that helpful?
But frankly most shops out there are not worth it, but if they are, let's talk about how. Many very smart people I know would willingly leave their high-salaried FAANG job for a more rewarding or interesting job even with a steep compensation cut -- and there are many places that would benefit from that talent -- they just need to learn how to recruit it.