Another use case is invasive species control in parks and large public lands. As an example, Portland has a large park that stretches along a ridge-line for about ten miles, and it's getting overgrown by English ivy, which kills the trees. It's a big enough area that pulling it all by hand would be very expensive. Ivy-pulling robots would be pretty awesome, but it's a hard problem. Vegetation is thick and the terrain is everything but flat. You'd probably need some giant hexapods or something just to move around, and maybe some kind of Ivy-grabbing appendage.
Just mapping out the ivy infestation with drones and image recognition software would be impressive. There's enough room for a quad-rotor to move around in theory, but it would have to have some pretty sophisticated obstacle avoidance algorithms.
Forest park is about ten square miles, and maybe a third is overrun by ivy. That's solvable by a sufficiently large human work crew, but it wouldn't be easy.
Developing, manufacturing, and operating a crew of robots just for this one particular ivy problem wouldn't be worth the cost, but invasive species are a widespread problem and are sometimes on much larger scales, like hundreds or thousands of square miles. At some point, using people isn't a realistic option. If we can solve larger invasive species problems for less money than a human work crew, then that seems like a win.
Just mapping out the ivy infestation with drones and image recognition software would be impressive. There's enough room for a quad-rotor to move around in theory, but it would have to have some pretty sophisticated obstacle avoidance algorithms.