Then you could ask: "Why does the US government have the right to do this?" I think the answer to that is probably the Outer Space Treaty which is signed on by most countries including all major spacefaring nations.
This may have been stopped (and still can be) if there was major uproar among the US populace or by other countries. I don't recall hearing much about that.
In any case, I'm not sure there is a sufficient reason to stop it. The biggest issue that I have heard about is the potential for a negative impact on ground-based astronomy. That's obviously not good, but I'm not sure it's a sufficient reason to stop this.
That’s not to say that individuals should necessarily be able to do whatever they please on things of this scale, but trying to make everybody happy is a great recipe for endless stagnation.