Technically, a single company can have products licensed for both closed and open licenses - I know, I work for one. They can even offer the same product under an Open Source license, and under a different license. Owning the copyright, they can fork the product, implement some features only in one version, and release that only under a closed source license.
Of course, nothing prevents anyone from taking a version that has been released under an Open Source license, and (re)implementing the features the company only offers under a closed license. Except that it requires time, effort, and know-how.
An order of magnitude???
In rough numbers, the mass of your normal human is one order of magnitude over the mass of the rover. The life support for said human would be another order of magnitude, or two. That would be fine, if we could leave the volunteer(s) behind on a dead planet. But getting them back would mean sending a big enough ship to bring them home. That would be at least thousand times bigger than what they'd need to survive on the surface - three more orders of magnitude. That's what I could think here and now. I believe there would be a few more problems to account for one or two orders of magnitude. So, my estimate for sending humans (that would expect to return) would be at least a million times more than to cost to send the rovers. With all these uncertainties, perhaps a billion...
Still, worth the effort, if and when we have the resources and technology. I hope to see that in my lifetime, or at least in the next 50 years!
Not all Open Source projects are funded by venture capital! I work for a small company that has several Open Source projects out there, and has never had outside capital. We've had our bad times, but at the moment we are expanding slowly, and the future does not look too bad.
(And yes, we use Twiki internally, and I got the "relaunch" mail. Sounded like they wanted "strong branding" that was "not compatible with Debian". Pity, but if that is the way it goes, I will need to find another Wiki system for us, and probably convert all our data - won't let any single application dictate what distro I should use. )
If you want to put yourself on the map, publish your own map.