* Very few recruiters outreach mentions any kind of compensation expectation. Why would I bother with hours of chat, screening and interview loops if I know only a handful companies offer the same kind of compensation I'm used to receive?
* The bar of a Senior position is quite high, so high that most Senior engineers would not pass it, it requires months and months of preparation. I would do that only if I was absolute sure I wanted to leave my current job.
* I would be willing to receive a little less if a company could offer something that I don't have like a better commute, work on something I'm more passionated about, etc... However, most companies think that working from home is good enough to justify a 50% lower compensation.
The only exception that I can think that compensation is not the main point is if you are trying to hire someone so successful and rich that money doesn't really matter for them. But my guess is that this kind of people are even more rare than senior people.