When France is viewed from abroad, the strength of its unions is taken for granted. And sure enough, as strikes over proposed pension reforms have taken off since early December, the English-language press has been peppered with references to France’s “powerful unions” and talk of the country being “paralysed” by strike action. If only.

In reality, the movement has revealed some of the limitations of French trade unionism today. While polls show that the majority of people continue to both oppose the government’s reforms and support the strikes, protest turnout has gradually declined over the course of several national mobilisations.

Meanwhile, actual strike participation remains low. On more than a few occasions, teachers, air traffic controllers, dockers, lawyers and Eiffel Tower staff have walked off the job. But by and large, strikes have been concentrated at essentially two major employers: the national rail system and the Paris underground and bus network. Over the last week, even these have seen walkouts ebb.

Of course, the battle isn’t over yet. With the national assembly expected to take up the reforms in mid-February – and the senate to pick things up after municipal elections in late March – disruptions could last for weeks to come. The sheer endurance of the movement is also impressive.

What’s clear, either way, is that while trade unionists have hoped for huge walkouts of private-sector workers, these simply haven’t come to pass. Instead, small-scale actions have increasingly grabbed headlines. Last week, for instance, energy workers cut off power to a major food market in suburban Paris and union activists clashed with riot police outside the Palace of Versailles as Emmanuel Macron met foreign business leaders inside. Another group of workers barged into the headquarters of the moderate General Democratic Confederation of Labour (CFDT), which backs the pension reforms. The anger is understandable. But in the absence of a sustained strike movement to complement these actions, it’s hard not to read them as a sign of organised labour’s weakness.

Why haven’t the strikes caught on more? One reason is, while French unions still negotiate contracts that cover nearly the entire workforce, membership is skewed toward the public sector and what’s left of the country’s old industrial base. Union membership has held steady for the last couple of decades – 11% of the workforce, down from about 20%in the 1970s – but organised labour has struggled to gain a foothold in the service sector or in the chain of subcontractors that increasingly define the economy. In other words, nearly all French workers benefit from unions, but few are actually in touch with them.

Even in those sectors where unions are a regular presence in workers’ lives, striking comes at a cost. In contrast to the US and the UK, most French unions don’t have well-endowed strike funds. That forces employees to make major sacrifices in pay when they walk off the job. A “solidarity fund” launched by a branch of the General Confederation of Labour (CGT) – the combative union leading the strike movement – has raised nearly €3m (£2.5m) from the public since the strikes began on 5 December. Yet the sum still pales in comparison with what strikers would receive if they stayed at work.

‘Macron’s government has towed a hard line with unions at the bargaining table.’ Emmanuel Macron addresses French businessmen at the Elysée Palace. Photograph: Antoine Gyori/Corbis via Getty Images

It’s hard not to think that unions could have been better prepared. After all, it’s not like this reform was a surprise. Macron has been promising to overhaul the retirement system since his 2017 bid for the Elysée. As Bruno Poncet, national secretary for SUD Rail (the most militant union at the national railway), explained to me, his union began gearing up for the pension strikes as early as last September, handing out flyers and organising discussions to build support for the walkout. Unfortunately, that sort of work has been rare: for many unions, the strategy appears to be putting out strike calls and crossing fingers that people jump on board.

Aware of these weaknesses, Macron’s government has taken a hard line with unions at the bargaining table, while offering up a few key concessions – perhaps most importantly, exempting police from the reforms. It has also caved in to the main demand of the moderate CFDT, agreeing to temporarily suspend a proposal to raise the earliest possible age at which most workers can retire from 62 to 64 (the measure hinges on unions agreeing to a separate set of cost-saving measures). Having neutralised these potential sources of unrest, authorities are banking on the idea that it’s politically acceptable to trample over the CGT and its allies.

The problem with this approach is that the left-leaning unions still speak on behalf of millions of French workers – and judging by the polls, the majority of French people. So no matter the ultimate outcome of the pension battle, the bigger challenge for organised labour is to transform these passive supporters into active members.

Devoting time and energy to recruiting members outside the traditional bases of support is essential. Poncet told me the country needs a better understanding of the role unions have played in its history, and he believes teaching more labour history could help. After all, much of France’s welfare state is the product of millions of workers going on strike – or authorities responding to the fear of just that.

• Cole Stangler is journalist based in Paris