Why collective wage agreements are bad

Collective bargaining has a few advantages over the alternative, each firm bargaining individually with each trade union. It allows to internalize externalities in the bargaining process. It reduces negotiation costs per firm and union, although it may take longer than for the alternative. However, it prevents individualizing contracts to local circumstances, something that becomes more important as the workforce is getting more human capital and more specialized. Finally, there is that thing with market power.

Xiaomin Cai, Peter Gautier and Makoto Watanabe try to disentangle some of these costs and benefits within a on-the-job search model where both sides are heterogeneous. There is a wage than a planner would use in this context, and it is uniform. However, absent the collective bargaining, you would want wage heterogeneity, because this allows for firms to signal to workers that they have higher labor productivity. Thus, it is better if firms cannot commit to the uniform wage of collective bargaining than if they can commit. A rather unique situation where commitment is bad. And in an empirically plausible case, it is even better not to be restrained by collective bargaining altogether.