The Gemara indicates that a person feels more busha (shame, embarassment) when a lower type , less important person insults him than when a more chashuv, important person does. What is the sevara behind this? I would think, intuitively, that a person would be more shamed if a King, President or l'havdil Gadol B'Yisrael insults him than if some person of little consequence from the street does.
I think that the answer lies in an opinion brought by the Aruch ha'Shulchan (CM 420:29). He says that some say that the worst embarrassment is from a regular person. This is because being embarrassed by someone who is a great person in Torah, money, or honor is sometimes worthwhile! It seems that he means that they can be imparting important information (although not in the best manner) to the person. A low person, according to this opinion, is not important anyway so it is not so denegrating. However, the mainstream opinion might hold that when a lower class person would embarrass someone (especially in societies where the difference in classes was emphasized, before democracy) it was considered unheard of and shocking that such a person should treat a more distinguished person in such a fashion, unlike the normal give-and-take among regular people.