It was John Steinbeck's intention to write Of Mice and Men both as a short novel and as a play. This is shown by the fact that a stage version of the work appeared in New York the same year the book was published, which was in 1937. It is also apparent in the text of the novella itself, which is limited to only two main sets and relies heavily on dialogue. The characters are always calling each other by name, and characters frequently introduce characters to other characters by name. This is invariably done in stage plays in order to enable the audience to identify the characters they are looking at. Since Steinbeck wrote the book with the play in mind, he limited the conflict to dialogue except in the memorable scene in which Lennie crushes Curley's hand and in the scene which ends with Lennie killing Curley's wife. Physical action on a stage is very hard to present and always looks faked. Steinbeck seems to be writing his book with the intention of making it easy to adapt to a play. There is also the final scene in which George shoots Lennie in the back of the head, but there is no conflict and no action. They are both sitting down.
There is a great deal of conflict in the book, but it is almost all verbal. Several of the men argue with Curley. There is a lot of argument and insulting in Crooks' room when Curley's wife is present and refuses to leave--but no violence. There is some conflict between George and Lennie, but no violence. There is some conflict between Curley and his wife, but it is pointless. The book gives the illusion of a lot of smoldering potential violence without the explosion. The mob of men hunting for Lennie surely intend serious violence, but it never happens. Furthermore, they are mostly only heard and not seen. The conflict is used largely to suggest drama in what is essentially a static environment. Curley's wife is frustrated because the ranch is so boring.
There is no conflict over wages or working conditions, perhaps because this is the midst of the Great Depression and men feel lucky to have any kind of jobs.