From what I understand it's due to two things-- at 34, I'm older than others going for junior positions. I spent a decade abroad after graduation and have only a year of experience at a tech start-up in Asia. I can kind of understand the pursuit of someone who already knows what they're doing, but on the other hand everyone has to start learning somewhere. Sure my bohemian background and experience starting and running a non-tech business and learning multiple foreign languages doesn't translate directly into usable skills here, but I would have thought that it would have been a strong signal I'm capable of working hard and learning quickly.
Not to overstate things, I am getting a lot of interest and a few interviews and even repeat interviews. It's just that things are moving very slowly, and I'm not getting a great return on the time I put into it. Also, SF is a very expensive city to live in off of savings earned in a developing country!
I think the shortage isn't so much general talent; it's a shortage of people who already have X skill a given business wants right now.