The funniest part about this is that you chose maybe the single worst example to support your case. Heres a news flash for you, they had flying cars in the 70s, literally. The reason they aren't everywhere is because very few people have a pilots licence. In other words, humans were to incompetent as a group to handle a simple technological advancement. However automated flying cars could follow very shortly after automated earthbound cars.
As for political will to stop it, thats another point where you just don't get how the world works. If Japan allows it, then everyone else has to or we lose the precious ability to "compete". When the US outlawed experimentation with the human Genome, did that stop the research? Not even remotely, Italy just became the center of it.
Not that it matters, even with your own theory Japan will experience a social boom time from their declining population. They will have a far more efficent workforce and that competitive advantage will only grow more dramatically as time goes on.
Jut out of curiosity, why exactly do you think there won't be robotic military and security? Based on current R&D work that will be one of the very first jobs automated.
