I'd bet it's just a function of what people are willing to do the job for. $93k gives you a very comfortable lifestyle, and tech workers tend to be much more motivated by the work itself than their peers. Those who really care about getting rich will go to SV and do a startup. So there's not as much pressure for increase.
Er...isn't the general agreement that if you want to get rich you absolutely should not go work for or found a startup but instead get a steady job at big corp and live below your means? People are always on about how shares in a startup should be counted as $0 compensation. Not to mention $93k doesn't go very far in places with large populations and high job prospects.
2) The general wisdom if you want to get financially well-off is what you describe. Those who'd prefer to risk it all for a shot at being filthy rich do startups.