A writer called Ulysses768 penned an article posted at Ricochet.com titled Why Are New Tech Companies So Liberal? (The word "liberal" should probably be replaced with "progressive," as the word "liberal" doesn't mean what it used to mean.)
So why are they? He sums up three theories, to wit:
The people are the same but the companies are more authoritarian. Motivated by a very competitive job market and empowered by financial success, these companies seek to engage with their employees at a new level. They encourage their employees to basically live at work, breaking down the professional and personal divide. This fosters an environment not unlike a university. Everyone must be careful not to offend and the needs of all must be accommodated at the expense of the few. The cultures of victimhood and blind acceptance find fertile soil, and people who disagree learn to keep quiet.
Newer tech companies are more software- and web-based than their predecessors. Therefore aesthetically pleasing design is more important to the success of their products. Therefore more creatives are required and creatives trend left of center.
College indoctrination has become so successful that it has bled into the hard sciences and engineering spaces. My fellow employees seem more liberal because they actually are more liberal.
Makes sense, although to this right leaning fly-over country blogger, the college indoctrination theory makes the most sense. As Thomas Sowell observed:
Today one can literally go from kindergarten to becoming a graduate student seeking a Ph.D., without ever hearing a vision of the world that conflicts with the vision of the left.
That certainly seems consistent with what we hear about college life these days.