Now this is a nice thing to believe - the only companies that hire women are the
good companies. I assume they're good by virtue of hiring women. So, company + hires women + pays them well => good company, good company => does well on the market. I don't think it stands to scrutiny. I'm not sure if you mean that those companies are morally good, therefore successful on the market (generally, the reverse is true), so I'll ignore this point, but I propose another interpretation:
The companies that hire women are the ones that can afford it. Seems more likely, but it would imply that women are less capable than men in this field. Assuming this is not true, with less women than men in the industry, you should expect proportional amounts of them in both "bad" and "good" companies. It should average out to equal pay.
Since it's not virtue, and not good companies being charitable, I smell only one other likely explanation: maybe it's profitable for companies to hire women as programmers now? If it's not because of merit, then how could it be? Maybe it's because it is fashionable nowadays to go out of your way to make it good for women, and you risk PR flop if you don't? Here. I smell sexism.