What you have to realize though, is not jsut the rate of pay, but also the rate of production. An American Employee who spends half his time lazing doing nothing or complaining of things while being paid, is COSTING his company money they get no return on. This in turn makes it even more expensive to do things in the US. I'm 19, the job I started doing, a "decent" employee could get it done in 30 minutes. A bad one an hour, or if in his own words "45 minutes, and that was realy pushing it".
Me? I've done it in just over 7 minutes a few times, and average a nice 10-15 depending on unforseen complexities.
You could pay the bad employe $7 an hour, and you get one unit per hours. I would work at 4-5 units an hour, so if you paid me $20 an hour, you would be ahead. If your forieng worker due to conditions was not able to match my production rate. Lets say if he had good conditions, he'd be 20 minutes per cycle, but due to tiredness and conditons that are not as easy to work in, he's 40 minutes. In two hour's , he has done 3 units, and cost $4. In two hours, I'll have done 12 units, and cost $40. I'm $3.33 per unit, he is $1.33. However, to keep the same production rate per day, you have to hire more of him. In one hour, 4 of him cost $8, only $12 off of me, and you have to pay for 3 more work areas.
I think a lot of why American's can't make it cheaper, is not just the cheaper labor costs, but how darn lazy we are. Outside of family owned and operated bussiness's, the effeciency is mind bogglingly slow in a lot of cases, except for automated proccesses perhaps.