There are two reasons for this:
1. It's cheaper to do business overseas.
2. There are more customers overseas.
The United States of America has become a tired, expensive place to do business, and doesn't offer the same growth prospects as other parts of the world. It's really that simple, and posting these "bring back American jobs" rants on FreeRepublic on any thread where you think they're relevant isn't going to do anything to change that.
I can tell you that all of this because I would love to open a business myself and employ other people, but I refuse to do so because I refuse to deal with a bureaucratic mess just to keep the lights on. This ObamaCare sh!t sure doesn't help, but the truth is that employer-paid health care is a complete disaster regardless even without ObamaCare.
In other words,
America is exporting jobs.
Taxes and regulations are killing the golden goose. My proposal would eliminate the income tax completely (repeal of 16th amendment) and all taxes on capital gains, interest and dividends. A big chunk of those trillions sloshing around overseas would pour into this country. The money flow would be phenomenal; liberation of capital such as hasn’t been seen in 100 years. Institute a national sales tax with rebates for low income. Social Security can be a privatized option for those under a specified age. It would be an economic freedom fest. Right now the USA has dropped to 36th in economic freedom. In a short time, the USA would catapult to #1, passing Switzerland and Hong Kong.