I think you are half right. It would take wars exactly like Irag and Afghanistan. And here we are, testing autonomous vehicles. Perhaps I'm wrong, but my understanding was the current raft of autonomous technology was supported in it's early stages by DARPA, with their priorities set by what was going on in Iraq and Afghanistan.

Someone I know frequently relays an anecdote. They were designing a new military helicopter. One of the requirements was that if the pilot was injured the aircraft should be able to return to base and come to a hover. They were trying to figure out how to cut weight. My friend said, well, if we just remove the pilot and all the equipment needed to support them, we'll lose a lot of weight, and the vehicle will be more aerodynamic. His suggestion wasn't taken seriously. That was before Iraq/Afghanistan.

That project got canceled, my friend retired. I have another friend working at the same company. They are building an autonomous helicopter.

*Edit: ok looks like someone else already noticed this: https://news.ycombinator.com/item?id=17600849