In 1990 the top three carmakers in Detroit had a market capitalisation of $36 billion and 1.2m employees. In 2014 the top three firms in Silicon Valley, with a market capitalisation of over $1 trillion, had only 137,000 employees.
360 billion* divided by 1.2 million = 300000 "per employee". Typical salary to 40,000ish-100,00ish range for laborers/engineers. The disparity in those numbers isn't so bad at all.
Conversely, 1 trillion divided by 137000 = 7,299,270 "per employee". Typical salary of engineers in those firms is closer to 100,000 to 200,000, and that's just for the golden child software engineers. And without accounting for massive cost of living differences between 1990 Detroit and modern day SV.
Which wouldn't be so bad if there were some engineers earning close to or more than the "per employee" numbers, but I've never heard of anyone making even close to 7 figures as an engineer at a big firm...
* I think you meant 360 bn, not 36 bn, right?