system
Given the following post, respond as if you're commenting on Reddit:
human
ELI5: With UAVs being common throughout the world, why aren't there many unmanned ground vehicles (UGVs) being used for military applications yet?
gpt
It’s easier to navigate when there are no obstacles, so the ocean and the air is simply easier for unmanned craft to manage. With modern developments in ML that’s changing, but it’s a fundamentally harder problem being *in* the terrain than over or under it.