75% of jews in France survived though, including 70,000 hidden children.

It's true that France before 1943 was still struggling to act as if the French Police (essentially in the northern part of France officially "occupied" area where Vichy didn't have much control) was still in control, so they were responsible to arrest jews (they literally asked for it to the germans). There was no really way to know what would become of them though, jews didn't really know either. Quota asked by the germans were never fulfilled though. Lots of french policemen could help some families still pretending to arrest, some policemen just did as asked. Even in places like the Vel d'Hiv were jews where regrouped some people just "walk away" while policemen were looking the other way.

Things like "also arresting the children" was seen as they would go to work camps with families, people thought that if you keep families together with children it would mean they wouldn't kill everyone, why bother? That's all those subtle decisions and the dilution of responsibilities that makes things like shoah possible in the end.

Some people though understood exactly what the horror mean and did everything they can to hide / go out of camps.

1 million french soldiers were emprisonned in Germany and the germans used them as bargaining chips.