Because the last thing a Labour party wants is for people to join unions...

The UK Labour leadership election is turning into a public demonstration of everything that is wrong with that party. First, the Blairites tried to keep the "unelectable" incumbent off the ballot, because otherwise he might win in a landslide like last time. When that failed, they then disenfranchised the hundred thousand members who joined in the last six months - unless they paid £25 (which, in context, is a third of the weekly income of a part-time worker in the UK - but pocket change to the Oxbridge toffs of the Blairite faction). Then, when people realised they could participate by joining a union (resulting in a surge in union membership), the Labour party disenfranchised them too. Because apparently the last thing a party which purports to be the political voice of the labour movement wants is for people to join unions...

And then in a few months time, they'll no doubt start whining about "voter apathy" again. But by slamming the door so firmly in the face of their own supporters, the UK Labour party has sent a very clear message: they are not interested in the views of voters, or even of their own members. Instead, both should shut up and do what they're told. Faced with this attitude, it is no wonder people turn away in disgust and pursue change through other, more democratic vehicles. At least that way they don't get treated like peasants.