> It's not clear why the DARPA robot didn't have thermal unless this is a really old story.
Who says it didn't? A thermal camera doesn't mean your targets are conveniently highlighted for you and no further identification is needed. Humans aren't the only thing that can be slightly warmer than the background, and on a hot day they may be cooler or blend in. So it's probably best if your robot's target acquisition is a bit more sophisticated than "shoot all the hot things".
Who says it didn't? A thermal camera doesn't mean your targets are conveniently highlighted for you and no further identification is needed. Humans aren't the only thing that can be slightly warmer than the background, and on a hot day they may be cooler or blend in. So it's probably best if your robot's target acquisition is a bit more sophisticated than "shoot all the hot things".