I often hear people saying phrases of the type "How are we doing over here?" by servers at restaurants, for example. Obviously they mean "How are you (plural) doing?" Where does this type of usage of "we" come from? Is this pronoun misuse a regional thing? Has it entered mainstream American English? Am I wrong in thinking that it is incorrect?
The patronizing "we"
The patronizing we is used sometimes in place of "you" to address a second party, hinting a facetious assurance that the one asked is not alone in his situation, that "I am with you, we are in this together". A doctor may ask a patient: And how are we feeling today? This usage is emotionally non-neutral and usually bears a condescending, ironic, praising, or some other flavor, depending on intonation: "Aren't we looking cute?"
A nosism is the use of 'we' to refer to oneself.
A common example is the royal we (Pluralis Majestatis), which is a nosism employed by a person of high office, such as a monarch, earl or pope. It is also used in certain formal contexts by bishops and university rectors. The expression was first used in 1169 when English King Henry II (d. 1189), hard pressed by his barons over the investiture controversy, assumed the common theory of "divine right of kings," that the monarch acted conjointly with the deity. Hence, he used "we" as "God and I...," or so the legend goes. (See Rolls Series, 2.12)