- Culture matters a lot in hiring. By this I mean a Stanford grad is much more likely to hire another Stanford grad in a field of qualified candidates. This isn't simply a form of nepotism as such. Two grads from the same college will share a larger common cultural base;
- The culture the founders bring shapes the organization. Many startups are started by Stanford and MIT grads. It shouldn't surprise you that this biases the makeup of their workforces and what they look for;
- Speaking as someone who has interviewed in the field of programming there are many frauds. I don't even necessarily mean deliberate frauds but there are clearly people who are employed as programmers/engineers who have no business being such. It's astounding how you can stump someone with 5-10 years of experience by asking them to code a simple loop (seriously);
- If people are worried about foreign labour putting downward pressure on wages, the indentured servitude that is the US work visa and immigration system should be the target of your anger. It allows bodyshops to hire people from, say, China and India and pay them a pittance because they know those people can't leave for 8+ years if they ever want a green card.
Make a green card automatic after, say, 6 years on an H1B, even if you change jobs, and a lot of those problems would go away.
As for other fields, I can't speak to those, other than anecdotally a lot of fields seem to have the earning potential of being a waiter in Manhattan.