As an impertinent question (2)

The seemingly never ending phone hacking scandal has prompted me to think about why some areas of public life are regulated and controlled - up to a point at least - while others are not.

So my question is:

'Why are ever bigger, more powerful, Labour supporting trade unions considered to be a 'good thing' in the public sector - yet ever bigger, more powerful, Tory supporting media companies are regarded as a 'bad thing' in the private sector?'  

I think we should be told.