Actually, this points out another possible explanation -- that distance is the effect of ethical behavior rather than the cause. This is not necessarily because the boss explicitly or intentionally demands unethical behavior from his subordinates. Often it's because bad bosses like to surround themselves with yes-men and toadies.
200 parts per million might be insanely rich, but it also means you have to process over 300 pounds of ore to extract 1 oz of platinum. That's nothing to a terrestrial mining operation which might crush several tons of rock to recover a single ounce of gold, but remember they do that with mass-is-no-object machinery and consuming, from a spacecraft point of view, unthinkable amounts of power. In space operations mass and power matters a great deal.
I'm not saying it won't happen eventually, but it won't be profitable until we're measuring cost per pound to orbit in pennies rather than thousands of dollars.
I considered the near Earth object case. Clearly that's the easiest place to return material from; the problem is that it's coals-to-Newcastle. So far as we know the bulk of that material is stuff that's easy to get here on Earth: silicates, sulfides, iron, nickel etc. Judging from meteors found here on Earth there are exotic materials like iridium, but in trace quantities.
While there's no doubt lots of valuable stuff like platinum up there, I think people are picturing it as floating around as nuggets of largely native metal. The platinum deposits in Canada's Sudbury Basin were delivered by a meteor, but that meteor was fifteen km across. It contained a lot of Pt in absolute terms, but in relative terms the Pt was rare compared to silicates or nickel. The liquefaction of the meteor in impact separated the heavy metals into convenient deposits. If we tried to mine that object while it was in space we'd have had to crush and melt a lot of ore to get much Pt.
Well, as I said it's an emotionally driven investment, which is not to say it's an irrational investment, so long as you understand that.
This might be just the thing to keep your solar-powered lunar instrument running for half the month.
It does not prohibit colonization, it just prohibits exclusive territorial claims.
Right, which does not necessarily prevent claiming materials found as private property.
That said, this is all a tempest in a teapot. At this stage of technology asteroid mining is about the worst imaginable investment anyone could make. It's a purely emotional investment, driven by enthusiasm, and it doesn't stand up to critical scrutiny. We don't even go after the valuable on the sea floor because the cost of finding and raising them makes that unprofitable. If there were hundred pound chunks of refinery-pure platinum floating around in the asteroid belt it would cost more to fetch and return them than they'd fetch on the market.
The economics of space travel is dominated by the cost of moving mass in and out of gravity wells and imparting the necessary acceleration to match position and velocity with targets. It follows that we're looking for stuff with the highest value/mass, and until costs drop by a couple of orders of magnitude there's only one commodity worth returning from space: knowledge. The first physical substances worth mining will be things useful in the pursuit of knowledge -- e.g. water that can be converted to rocket fuel without tankering to the outer solar system.
"Everybody is talking about the weather but nobody does anything about it." -- Mark Twain