Move faster for a short time.  They could certainly fly down trails looking for people via image recognition, but its hard to compare than to a person walking a trail for 8&#x2F;10&#x2F;16 hours looking for all sorts of signs, even smells.<p>Many lost humans are also nowhere near trails.  Old people, people with mental issues, and young children often actively hide from searchers.  Flying robots might not get the results one would expect.<p>Dogs.  Dogs find people.