Are public sector unions a fair target?

I have no issue with workers organizing collectively to increase their bargaining power in an effort to maximize what they receive in pay and benefits.  

That's capitalism. Business seeks to maximize its return, so why shouldn't workers?

And if unions are perhaps too successful, and the wages and benefits being paid are more than the employer can bear, then everyone loses.  Mutual survival is a strong incentive at the negotiating table.  Ask for more than what the marketplace can support, and instead of standing on a picket line you'll be lined up for unemployment benefits.

But that\s the private sector.  What about the public sector?  

A different ball of wax entirely, the dynamics aren't the same. Unions aren't negotiating with a business that has to earn a profit when dealing with government.  Instead its taxpayer money and deficit financing that governments must rely on.  

Here in Quebec City the current mayor is running for re-election and is expending enormous political capital in taking on unionized municipal workers, seeking a mandate to negotiate major concessions in the area of pension benefits.  The point is made that with the current funding deficits, taxpayers with no pensions will be seeing their tax bills increase to pay the pensions of retired civil servants.  

There are no easy answers to this question.  Nobody likes to see gains made over the course of years lost, whether its in the public or private sector.  Private sector employees, many unionized, have seen their pay and benefits frozen, eroded, or even lost completely.

Everyone should share in the good times, but likewise when resources are limited no single group should be completely immune to economic reality.