I think he was asking why the USA has no mining machine manufacturers.
I believe it probably does have to do with labour. It also could be tariffs on certain stuff that is required to manufacture them.
The answer is still at least partially right since the production of miners requires a lot of energy as well. Add labour to that and the costs of materials and you'd have a pretty accurate answer to OP's question. About everything is cheaper there, so the question is..
Why would you buy a more expensive equipment just for its country of production?