Imagine how easy it would be to make a remote-controlled or even fully autonomous train or monorail, but that isn't ever going to happen.
The technology already exists to make fully automated passenger airliner flight (far simpler than the tech that goes into making that K-MAX work too), the issue isn't a technological one, it's a moral one. Two pilots checking each other and the aircraft systems, with their lives just as much at stake as everyone else's is the point.
Even if you had a significant enough portion of the population who was willing to fly on such a jet, could you imagine the outcry and lawsuits that would take place in the event of an incident? It wouldn't even have to be a total-loss crash. A similar argument could be made for cargo planes, since they endanger other peoples lives even if the jet has no one on board. This is the same argument for rail freight. Exceptions like the K-Max are simple; the threat of the chopper crashing into something or someone is pretty low, and the extent of the damage would be limited. It also mostly only effects the military anyway.
Just like flying cars and autonomous cars, it really makes my laugh to see companies throw tons of money at these projects. People can afford to have flying cars, they're called helicopters, you don't see many people flying them because of the safety, financial, and legal limits, not the technology. Watching Dr. Moller and his going-nowhere skycar project is pretty sad. Now seeing Google working on their no-one-is-gonna-buy-those-things-anyway car is just as sad (but also a bit funny).