Fridge Brilliance: Why can't Luke placate Claudia when he readily speaks with most animals and even knows exactly how to calm down the hungry pitbull in Diabolical Box? Simple. Claudia, like the rest of the town, is robotic.
Fridge Logic: You're told that the robots shut down after a while and need to be repaired. This either means the village will shut down anyways after a while, meaning leaving the treasure there was pointless, or it dooms Bruno to repair robots there for the rest of his life with no purpose anymore, since "the apple" is found.
It is safe to assume that Bruno met some trustworthy human friends offscreen so that he can pass the role once he pass away. Also, it was said that taking the treasure would lead the robots to stop functioning completely. The treasure is like their life force. Additionally, Bruno is kind of old so might as well live his life to the end in said village.
Fridge Horror: Suppose a resident of St. Mystere ever, say, decided they needed surgery? Or somehow dismembered themselves? Imagine how utterly confusing and scary it would be for the villagers to find out that they're actually robots.
Robots don't need surgery and it is safe to presume that Bruno made sure that they keep out of trouble and if an accident did happen, Bruno can just erase their memories anyway since it is easier to deal with robots than humans in terms of personality overwrite.