I like the parallel you draw between space exploration and a past event in human history. And I do have to concede that governments do play a role in such affairs, reluctantly so though. I don't believe in governments being involved for the best interest of the people. As it was in the early days of aircraft, the most likely application for space technology is military superiority. Infact NASA and the US military have quite an intimate relationship that most if not everybody already knows about. There's an article in this month's PopSci titled "Battlefield: Space", which talks about the newly rekindled drive for space superiority as seen in the USAF and DARPA... It's just disturbing.
Now, something like this I wouldn't shudder at. A fixed percentage pan national tax on all companies that profit from space. It would place the responsibility of how that money is spent on the shoulders of the individual nations. There's a way that it can be specified later on, so that the tax is only a percentage of profits generated in the earth markets rather than the total profits. That way future colonies or independent human establishments do not fall under the same category.
As for labor problems, even if these are to be unmaned missions there are people who have to build the machinery and are not in administrative positions. So I understand where that concern comes from. I can't think of a way to prevent that.