> if these were truly easy jobs someone would have figured that out and won by hiring cheap developers with non-traditional backgrounds
Note that the same argument works as evidence against recruiting bias and pay disparity. Discriminating against people or paying them less due to factors unrelated to job performance is leaving money on the table. Such discrimination persisting would imply that the market is very inefficient in this aspect.
The fact that many of the web companies want to crowd everyone in a few hundred square kilometers of the Bay area demonstrates that they don't know what they are doing and are leaving money on the table. That doesn't disprove the fact that women are somewhat more uninterested in pursuing those jobs than men are.
Note that the same argument works as evidence against recruiting bias and pay disparity. Discriminating against people or paying them less due to factors unrelated to job performance is leaving money on the table. Such discrimination persisting would imply that the market is very inefficient in this aspect.