The short answer is that most countries waited for private individuals or businesses to bring them designs and then tested them.

France had a history of working through state-owned arsenals that would work in secret without patents. The French had a mindset of "revenge" for the Franco-Prussian war and were obsessed with out-designing the Germans.

So they focused on advantages, and were one of the few powers to see widespread auto-loader use as an obvious gain. Others still doubted it frankly.

They had programs in secret which meant slower development. They also had a problem with 8mm Lebel. It was basically just necked down 11mm Gras. Being the first smokeless cartridge, they rushed it into production to "beat" the Germans in 1886.

It was not future proof and it's odd shape and thick rim meant auto-loading it was difficult. But it was produced in the millions already with rifles and eventually machine guns chambering it.

No single auto-loading trials rifle had enough strength to replace both the existing bolt actions and justify replacing all of the ammunition in service.

So they stagnated until the war broke out.

Then some of the technology on hand was wrapped into a serviceable 8mm rifle using the current cartridge, but it was too little too late to make a big impact.

Another rifle, the Meunier, was much better and could have made a bigger change. But it chambered a new, proprietary 7mm cartridge. Supplies were hard to keep separated and moving to the guns.

In summary: the French were focused on beating the Germans at everything. But were already married to an out-dated cartridge and could not change it easily. Auto-loaders could not use it easily. Everything stagnated in committees until it was too late for major changes.

(note this leaves out a LOT of nuance)

Follow up question, if this is true, why didn't they crush the Germans?