<Snipped quote by Revans Exile>
Traditionally robot soldiers have always been portrayed as predictable and rooted in their preprogrammed behaviour patterns, while biological soldiers can adapt and improvise during combat in ways the robots would find difficult to emulate.
PLus robots are more expensive than humans, and more difficult to replace. :p
You are talking about a programmed robot that only acts on certain preprogrammed behavior patterns, these training drones are artificially intelligent. An artificially intelligent robot can think for itself. That is like comparing apples to pennies.