The people are the robots in this case, but there are only minutes of hand labor in a phone. The labor issue is a red herring, despite the postings of the surrogates that magically appear every time the issue comes up.
Pass whatever you're smoking this way. 140,000 workers at 40 hrs. per week for a full year, divided by 72MM iphones per year works out to be about 3.75 man hours per iphone. I've seen estimates of about $6-$7 per iphone in assembly costs--and at $2 per hour, seems this estimate may be in the ballpark. Even when you start shocking those numbers, it is far in excess of the minutes per iphone you claim. In addition, all of the parts come from contries that have extremely low wages--so if you were to actually bring the iPhone to the US, the price would skyrocket.
The savings come from tax dodging, no pesky laws about dumping stuff in the river, no problems with dealing with any human issues. Just give them an order and in time containers full of iPhones appear.
The tax savings only comes from foreign sales. US sales face US taxes. And when they repatriate those funds, they'll be subject to tax. Unfortunately for all taxpayers, they're waiting for those "tax holidays" the government does every 5 years or so as a handout to the big corps. I think the next one will need to wait until a Republican is in the White House.