Is there a name for the natural human guilt complex? Humans tend to have guilt complexes, which prevents them, for example, from taking too many samples from Costco. Is there a name for this phenomenon?
Short Answer: I'm not aware of a specific name for this, but I would describe it as guilt-proneness, and it is almost always associated with a high degree of conscientiousness. 

Long Answer: Conscientiousness is one of the five major personality traits. People with high levels of conscientiousness feel strongly compelled to adhere to societal norms and rules, and will experience more guilt when they fear they've broken them. If extreme, in combination with other criteria, it could be classified as Obsessive-Compulsive Personality Disorder (OCPD). The DSM 5 lists eight diagnostic criteria for OCPD, one of which is "overconscientious, scrupulous, and inflexible about matters of morality, ethics, or values." However, in the absence of OCPD criteria, if I was writing a psychiatric impression of someone like you describe, I would probably say that person demonstrates and high degree of conscientiousness and is prone to guilt reactions in the face of perceived violations of his or her morals.