Why would scout robots be used for recon only, not general combat?
I have a situation in which scout robots akin to mars rovers are used for military applications by forces residing on a foreign planet (Mars) that operate out of colonies to keep civilians in line and exterminate raiders. these bots are equipped with imaging and video cameras, audio recorders, and a submachine gun-esque weapon chambered in 9mm. These autonomous (supervised) terrors would scutter around on six legs instead of wheels with solar panels for extended missions.
After the situation is evaluated, the scouts would de-activate and wait for human support, in the form of massive 12 wheeled armored tank-esque troop transports to arrive, clean up enemies, recover stolen goods and bring the autonomous scouts back to a colony.
Why would sending human soldiers be necessary to fight human raiders and outlaw bands, if the technological level is high enough to send combat-capable autonomous robots to fight instead?
keep in mind that the question is not "why is it necessary to send humans", but "why is it necessary for the humans to fight?"
