They wouldn't cost that, BOMs suggest the percentage of overall cost for high end smartphones attributed to assembly is much less than 10%. Even if you say it was 10%, and you say it costs 5x more to do it in the US, that only increases cost by 50%. Worst case that means the sales price increases by 50%.
In the real world there's no way Apple/Foxconn would use the same number of people to assemble iPhones in the US that they do in China if they were forced to make them here. It would be far more automated, meaning more capital cost but much less not more labor cost. Apple already builds a robot for each model of iPhone to disassemble it for recycling. While robots to do the reverse would be more difficult to make, they are certainly not impossible.
Biting the hand that feeds IT
