The reason is that France's level of unionization is not significantly higher than that of other industrialized countries. It just seems that way because of widespread sympathy for strikers--particularly public sector workers. It's "we're not going to take it, but we don't know what'd be better anyway." This gives the government the chance to set the agenda with higher-profile unions by channeling their energies towards interest aggregation, which is preferable to allowing more hardcore elements set the agenda:
Government officials also know that the interests of social stability are best served by not alienating the unions. In fact, in France stability will come from even stronger unions – which is exactly what the government has tried to do with the recent reform to base collective bargaining power on election results.
The problem has been that there are too many unions chasing too few members. Individually they have been so weak that their best leverage has been through strike action – largely in the public sector. The logic is that reinforcing the biggest unions, including the hardline CGT, will help to create a higher quality social dialogue and force them to negotiate, as long as the government sets down some clear rules.
That means Mr Sarkozy may throw a few symbolic crumbs to unions after this Labour Day protest. Far better that recognised unions score a small victory and continue to channel the discontent than to leave the way open for more radical, and potentially more violent, elements to profit from the malaise.
That said, there is always the chance that a single incident could spark off a flash of anger that no one will be able to control. As one official said recently, France is an eruptive country and the game will be to prevent that first incident from taking place. But equally, he admits: “The most serious incidents are the ones you cannot predict.”