Because it's politically incorrect to point this out.

FTA: >>Recent data from those companies and others like them confirm what everyone has long known: Most of their employees are white and Asian men.

Note that, at least for the UK, asian includes people from India. I don't where you are, but the tech scene I see in the bay area has plenty of white, asian & indian people in it. In contrast, I've only run into one other african-american engineer in my 13 years in tech... and he was first generation Nigerian(like myself).

Asian (don't forget Indian is included here) cultures are very different than black or latino cultures. Also, many Asian tech workers are first or second-generation immigrants, which is very uncommon for blacks and still fairly uncommon for latinos. This results in very different work ethics and parenting ethics.

Don't forget income. Asian family incomes are typically much higher than black and latino households. The parents are more often found in high-tech jobs which gives their offspring a big jumpstart. A black or latino parent might work in agriculture, food services, or low-skill manufacturing jobs and they aren't bringing a PC home to do work on, or have enough money to purchase one for their kids.