I'm deeply concerned about the ignorant place some of the anti-unionists come from here. The reason that individuals are able to bargain more strongly with employers now than in the past is because of the complex and supportive employment law environment we have, that includes legal protections placed on tribunals, disciplinary processes, and retirement and redundancy practices. That complex and supportive employment law environment would not be in place if it weren't for unions building it up and negotiating hard. Sensible management practices like letting an employee know of any performance concerns and allowing an adjustment period (rather than just firing someone who thought, reasonably, that they were doing their job effectively, but didn't know management were unhappy) were not taken up by managers, despite their clear effectiveness, until unions challeged them in the courts.
Organisations that have strong union presence have far better retention, recruitment, positive staff development policies, and management practices than competitors do in the same markets .. and this translates to better performances.
Where you have poorly performing companies with strong union presence, this is largely where management practices are significantly behind current good practice thinking, normally (as is the case in the NHS, network Rail, London Underground) where promotion into management is largely through longievity rather than ability or where management is seen as a purely academic discipline (eg HE, civil service, local councils etc).
It is important also to recognise that where industries like the motor industry are failing here, where union activity is relatively weak in the UK, competitors eg in Germany, france and spain who are consistently out performing us, have strong union input into decision making that is written into legislation and taken account of by parliament.
In a world where we need team functioning to outperform others, having management who won't listen to front-line feedback (often because their public school background won't allow them to take criticism from the lower orders) won't help - sure it will help that class to cream off the income, but it won't help the organisations to perform..
what is really concerning is that some here have posted that 'businesses need to get rid of bad employees' without ever considering that some of those bad employees can be managers.. and that is where unions can often most help large organisations in revealing poor management practice that is hidden upwards but very obvious downwards.