This is just more evidence that the current economic system is going to need to radically change with the advent of mass robotic automation. Taxing robots is like saying we need to take this new technological advance and shoe horn it into an existing system that is becoming antiquated. That's complete nonsense. Let me put this in perspective, let's take something that tax dollars pay for, I don't know like highways. If we automate that type of labor with robotics we don't need as much tax dollars for that right? Because we don't have to pay the robots. What we really ought to be doing is looking at how robotic automation affects everything not just the private sector. We need to dig into the details to see what the most rational, pragmatic thing is to do before we have knee-jerk reactions like "robots should pay taxes". Bill Gates is a smart man. It's quite possible he presented this idea not because he thought it made sense but to at least get people thinking about the issue more seriously.