When it comes to a single tech company, just by the reason of statistics, I can understand how it's hard to worry about diversity because you're basically taking a small N sampling of the distribution. When you're talking about all tech companies as a whole it makes more sense...and similarly, all colleges, or even individual colleges, who tend to enroll a larger sample of the population.

Of course, when we're talking about Google or Facebook, we at big N territory, so if you don't expect biases, the make up should reflect the general population.