Or do you believe in out-of-sight-is-out-of-mind?
In ideal world businesses would have to pay a fair livable wage, no matter where they build factories, or receive migrants from.
> It's not migration itself that is the problem, but the fact many migrants are in a position where they can be exploited more easily than native workers.
Well, if you let people migrate easily and legally, they wouldn't be easier to exploit than native workers.
Obviously the migrants wages would be relatively higher, and the locals' wages would be suppressed. Typically locals' needs are the (reasonably) top priority for elected officials.
Why would the locals' wages be suppressed?
In any case, we could try to figure out how much locals' wages would be suppressed, then tax the migrant workers that amount, and pay the locals. Seems pretty straightforward.
That doesn't seem to be what's happening though.
Let me echo back what I understand to be your argument: “If there were accelerating returns to capital moving the equilibrium of labor/capital-intensiveness mix, then there would be no demand to further reduce the cost of labor”
My argument is: regardless of where that equilibrium is at any given point in time, it will almost never be 0% labor-intensive, and anyone engaged in labor-intensive production would always have a preference for even lower-cost labor.
So the answer to the question of, “why do businesses want immigration despite a more capital-intensive mix of production” is “because cheaper labor is better regardless of how much labor you need.”
You're replying to basically a strawman I wrote. I didn't say that is what's happening, I said that's what would be happening if investment was all going into capital and not labor intensive industry as OP said.
EDIT: Oh, OP is you! No wonder you're getting touchy. Your original comment is wrong.