There isn't an above-baseline sexism among long-term professional programmers. Sure, there are bad apples, but the culture that you'll find at a gray-haired research lab or even a more traditional, supposedly conservative, enterprise shop is not nearly as exclusionary as the supposedly progressive and new Silicon Valley culture.
By stereotype, you'd expect 60-year-old men writing elevator controllers in Indiana to be far more sexist and exclusionary than 25-year-olds in California. It ain't true. First of all, someone who's 60 now was born in 1955 and has no meaningful memories of the bad old days; by the time he or she was starting a career, women were already in the workforce and it was accepted by many as a good thing. Second, if you control for education, the age vs. exclusionary behavior correlation goes away. Third, most people actually get more mature with age, and while there are some who mature at a lesser rate than society advances and become the "racist grandparent" trope, I don't think that it's the norm. (Also, American society's rate of advancement has slowed in the past 30 years compared to the 30 before that, but that's another topic.) Fourth, anyone who thinks the dominant Silicon Valley culture is still liberal has been asleep for 20 years.
That's not to say that private sector tech doesn't have a sexist, exclusionary culture. It does. It doesn't come from the programmers (although there are individual programmers who are assholes and keep it going). Rather, it comes from the mainstream business culture (MBA culture) that colonized us. In fact, the sexism of the Damasos (see: https://michaelochurch.wordpress.com/2014/01/05/vc-istan-8-t... ) who are sent West to boss nerds around is a lot more severe than that of the mainstream MBA culture. Banks might make it harder for women to advance; venture capitalists, on the other hand, will outright hit on them and threaten to "pick up a phone" and make them unfundable if they don't acquiesce.
You know how when a criminal gang kicks out some of its underperforming members and they form a new gang, the upstart young gang is typically more violent than the one it splintered off from? The sexism of the VC bros and the Spiegel types they fund is analogous. The demigods of the Valley are people who got kicked out of mainstream business culture because they weren't smart enough to do statistical arbitrage at hedge funds, so they were sent West to man this colonial outpost (from the MBA-culture perspective) called Silicon Valley. As MBA-culture failures, it's not surprising that they amplify some of that culture's worst traits, and that they've created a dominant culture in Silicon Valley that is (a) very negative and (b) far worse than the more superficially conservative (no sandals at work) but generally professional culture you see in more traditional companies, including the ones doing (say) hardware work and low-level programming, the latter of which seems to be the OP's interest.
She had a positive experience because she was hanging around Real Technologists, who aren't nearly as sexist as the Silicon Valley wunderkinder. The Shanleys of the world aren't complaining about 55-year-old men who still say "Oriental" (meaning no harm, and not holding racist views) but are generally professional and not very sexist (many are married and have daughters). They're complaining about 22-year-olds who get funded to the gills because they were in the same rape frat as a leading VC, and who go on to create horrible work cultures.