You're comparing apples to oranges. The trailer has all the amenities of a house. Power, water, stove, fridge, sink, bathroom, TV, heat and a/c in most cases. The tent? That's like the storage shed out back.
Comparing apples and oranges like comparing a IPhone to a Motorola flipper?
And you're saying Apple BUYS the phone from some production facility in China. I'm assuming they have their own factory there that produces it. Much different cost structure.
FoxConn is the assembler for iPhones. They also assemble smartphones and other devices for other companies as well. Maybe your phone too?