I'm perfectly aware of why latin binomials are used. However, even scientists do use common names. Some groups (birds, for example) even have "official" common names.

Along those lines, there is one, and only one, reasonable interpretation for what constitutes a kingsnake, and that is that it corresponds to the genus Lampropeltis. Furthermore, there is no rational way to define what a kingsnake is that includes all the snakes currently called kingsnakes without also including L. triangulum.