The point I'm making in my comment is that "Senior Software Engineers" are not making >600K in SF.
"Senior Software Engineer" is a role you can reach in 3-8 years of experience.
"Staff" is a whole different ordeal, a role many never reach. And even then compensation is closer to 450K; you might find some around 600K but those are outliers (whereas OP made it sound that >600K is something common)