Dick, indeed, a song is not an essay, that is what I wrote. Nevertheless, they have in common that they can sound "snobbish" (or "sanctimonious" or like manipulative propaganda), either on purpose or unintentionally, but need not necessarily. A lyricist who wishes to convince the unconvinced, and to gain a reputation among sensitive audiences, had best avoid that sound. Even angry or sharply satirical songs need not be "snobbish" in the sense of indiscriminate and apodeictic. Tom Lehrer knew that.

The problem is not restricted to social comment in the narrow sense. Quite a number of songs state some fact such as "Milk bottles are made of plastic nowadays" and directly continue "- doomsday has come". Those of us who like plastic milk bottles will not be convinced, and may in fact think "that snob should be glad to have milk at all, even brought to his door every morning without being woken."

As I wrote, the listener or reader of lyrics and other poetry must do more work than the reader of an essay, but so must the poet.