Unfortunatly, the jest of my remarks in the answer had not played in my favor. But I was deadly serious. It's sad that the one who voted me down didn't say or ask anything. But whatever...
So as to develop my point of view, I should say that even I think that in much countries (as in france where I live), unions are often the preffered means for workers to organize, that doesn't mean that these structures as political or syndical organizations reflects or represent the real interests of workers or the "working class" (which, in an traditionnal or even anarchist definition shouldn't limit itself to people who actually work : but those in general who are forced to work so as to survive). In this country (in france), the CNT (the anarcho-syndicalist union), even there is a lot of critics to make about it, is the only union where you can't unionize if you are a cop, a boss, or a prison guard, or working for the government. Which mean that in most of the others, you can unionize whatever the place you occupy in the production process (even it's a place of represssion, surveillance or employing one) ! A lot of "little bosses" (as cops or security employees, or prison guards) are members of the CGT or other unions : just because these little bosses are departements managers of foremen who are themselves employed but with a much more significant income, much power and responsabilities in the company, and sometimes a capital. Which means that you can be in the union, being a employed worker in high middle management : that is to say that you are both a member of the ruling class, the employing class (for exemple if you work in "human ressources"), and a simple employed worker. This is nowaday the situation of many bosses in the production process, who controll a simple unit of a big company, and have a big capital but are also employed workers who can be fired. They are in fact workers but not simple proletarians. The fact that these people unionize doesn't mean that they challanged their oppressive position or their social roles at all... But mostly that the union defends these social roles as long as they "should be rationalised and regulated".
Plus the vast majority of the unions protects and defends the "interests of the working class" as long as they coincids with capitalist projects (and also as the nuclear industry, the prison system construction sites, detention camps, working with absestos... etc...). Which means that the interests that unions defends are in general not revolutionnary and all, and in fact coincids mostly with those of the rulling class as long as their only real stance (which they share in common with the employing class and the ruling class in terms of capital, wealth and power) is workerism and laborism (and most of the ideologies that flatter Work). But today, work is embodied by the wage system. Finally, it's important to emphasize the fact that the MEDEF (french union of bosses) are found almost all the time at the "negociation table" with the "working class trade unions" and sign the same projects, the same chords, with the same arguments... This is a obsolete and false argument to pretend that there is the "good and honnest unions" or "honnest delegates" on the one side, and the scabs and bureaucrats on the others. Sometimes, scabs aren't even members of unions, but all delegates and unions leaders are scabs and/or bureaucrats, and those who follow them are also scabs. And workers interests only become revolutionnary and they overflows the frames of the unions and the routine ways of workers' revendications and protest (which are today virtually integrated to the interests of Capital and the employing class).
The fact that they both share the wage system doesn't mean that they really share interests in common -or that it's their real interest to do so-, but that in the limits of unions, they actually do most of the time.
That's the way it fits with what I say. But this is not new at all. If you read Malatesta or Berkman, they were saying aproximatly the same about unions (so less vindictive maybe because at the time the conditions were just not the same, but they were already very critical) : they allow workers to organize and are some kind of "schools of solidarity", but are not revolutionnary at all...
"Syndicalism (by which I mean the practical variety and not the theoretical sort, which everyone tailors to their own shape) is by nature reformist. All that can be expected of it is that the reforms it fights for and achieves are of a kind and obtained in such a way that they serve revolutionary education and propaganda and leave the way open for the making of ever greater demands. Any fusion or confusion between the anarchist and revolutionary movement and the syndicalist movement ends either by rendering the union helpless as regards its specific aims or with toning down, falsifying and extinguishing the anarchist spirit."
Errico Malatesta "syndicalism and anarchism" :
http://www.marxists.org/archive/malatesta/1925/04/syndic1.htm
and also :
"Now, then, you might justly ask, ‘What is the use of the union? What are the union leaders doing about it?’
The truth is that your union leaders do nothing about it. On the contrary, they do everything they can to keep you a wage slave. They do it by making you believe that capitalism is all right and by having you support the existing system with its government and ‘law and order.’ They fool you by telling you that it can’t be otherwise, just as the boss the school, the church, and the government do. In fact, your labor leader is doing the same work for capitalism that your political leader is doing for the government: both support and get you to support the present system of injustice and exploitation. "
Alexander Berkman, "the trade unions" in "what is communist anarchism" :
http://theanarchistlibrary.org/library/alexander-berkman-what-is-communist-anarchism#toc13
and Finally :
"During the revolutionary event the presence of a strong syndicalist organisation or party in the traditional sense has the immediate consequence of the proletariat being declared immature, and the conclusion that someone — syndicalist or party leaders — must decide for them. A structure for intervention is imposed on the base. Syndicalist or party meetings are always led by the same bureaucrats and specialists. Everything ends up passing over the heads of the workers. "
Aflredo Bonanno - " A critique of syndicalist methods" :
http://theanarchistlibrary.org/library/alfredo-m-bonanno-a-critique-of-syndicalist-methods#toc9