<<The unions are middlemen in the sense that they take a cut from the members pay in order to finance whatever value added services they provide.>>
The unions are basically the bargaining agents of the workers. The workers unite with other workers on other jobs and hire people to be their bargaining agents. But at all times the union exists only as the representative of the workers. OTOH, if the workers choose not to join, the union still has an independent existence of its own, with or without them. They provide a service to the workers who choose to affiliate themselves with the union.
Is everyone who provides something to the workers a middleman? If the workers pay a cut out of their salary to the store that sells them the workboots that they have to wear on the job, is the storekeeper then a middleman?
I guess the workers are an integral part of housing production, and so anyone that is essential to their function (the union, for example) is also an integral part of production rather than a middleman.
OTOH, speculators are not an essential part of the production. Neither are their lawyers and accountants. Multiple owners of the housing inventory, each with their own pack of lawyers, accountants, advertising agencies, real estate salesmen and women and property managers are all parasites and middlemen because if all the land were owned and financed by one entity (the state) there would be no need for 99% of them. None are essential to housing production, as Fidel Castro, and before him, Joe Stalin, proved conclusively.