So clearly there is some kind of difference between these places, no? Some reason why one place offers more opportunity than another in tech?
SV has an incredibly high density of headquarters of the biggest tech firms. This is where the leadership is, where the most experienced engineers are, and where the institutional knowledge resides.
Because attention is scarce and communication is costly, firms tend to keep the most strategic efforts closest and push less critical efforts farther out. As Dan Kaminsky used to say, "If you're not at HQ, you're not part of the conversation".
Individual contributors can be remote and support/sales/backoffice staff can be in satellite offices all over, but the key roles will be concentrated around HQ.
Now go back to finance. There are lots of bank teller jobs in Phoenix. Wells Fargo has a lot of staff there, so does Bank of America. But if you want to have a career in finance, you are going to have more opportunities in NYC where the HQ of so many FIRE firms is concentrated, and not in Phoenix, even though there are lots of bank tellers and back office managers that work in Phoenix.
The types of jobs you can have are just different. The opportunities, institutional knowledge, mentoring opportunities, social networks, level of responsibility -- it's different. It may seem unfair, but that's how it goes.
NYC is basically Phoenix when it comes to tech -- a lot of backoffice and sales positions, and a bunch of engineering satellite positions, but not a single major tech company is headquartered there.