"According to a report by Bloomberg, the labor cost for assembling an iPhone 12 Pro Max is around $10."
https://smallusefultips.com/how-much-money-does-it-take-to-make-an-iphone/
The problem for Apple is that their subcontractors won't be allowed to break the arms and legs of American workers.
And they might have to pay triple the wages. So $20 / phone.
The problem then for Apple customers is that bluecollar Apple assembly-line workers would then be owning late-model iPhones.
The assembly is the easy part though. You could do it at your kitchen table if Apple sold you a kit with the parts Ikea-style. Don't read too much into it. Making parts like the CPU or screen or what is much harder.
The fixation on assembly is a leftover from a time when things were made from much simpler parts like a pair of jeans made from fabric and buttons. In that case the assembly is a bigger portion of the actual work and bigger portion of skills.
Yes, but which is performed by robots, who demand the same pay in every country :p
