Let's imagine for a moment you're a PhD student - you're supposed to defend your thesis before your hand-picked jury in a few month time.
You've worked hard for the last three years on your subject. Which happens to be of the utmost importance for you, that's for sure, but that's also true for your lab's management, the industrial counterparts and, to be fair, lots of people from ecologists to economists and maybe, nowadays, everyday people.

That subject deals with the reduction of poluting chemical emissions during motor combustion (the reason you were receiving a scholarship from the car industry).

During your studies, you have also developped high level skills that were not directly linked to your subject, like mathematical modeling, non-linear optimisation and C++ coding. Up to the point where your lab's management asked you if you wouldn't mind staying there for another two years.
Ah, that lab happens to stand in the oldest, most respected, german university, Heidelberg, Baden-Würtemberg, Deutschland.

Now, imagine you have published articles, and been offered to write your own chapter in a to-be-released book published by prestigiuous Springer Verlag.
You've met numerous influent people through forums and actual convention. You've travelled to the four corners of Europe.
You've been offered a post-thesis two-year job in Cambridge, UK.

When you come back from that last convention, you're flying high on really good vibes.

But then, you remember you're French.
You also remember that your girlfriend is also French.
And your eventual problem is that you'd like to come back later to your own country.
So, you ask your Master II(Recherche) old teacher what should be done, and if you have any chance to get a job in France.
Why not take part in the usual process, to become maître de conférence, to prepare your abilitation à diriger des thèses, etc.

And then, from the 10 000 miles you were flying up in your personal heaven, you fall down in a minute or so to the ninth level of Hell.

And you remember the words "préférence locale" and "cooptation".

You're explained that jobs are fine-tuned so that the only candidate who can be chosen is the locally sponsored one(usually a former PhD student from that recruiting lab), precisely what you cannot be, since you've studied first in Germany and then in the UK. Your having a French double-diploma cursus of engineer (ingénieur civil des mines)/research student is of no use.
You have no chance, however remote to get a job in the public reaserch system.
Apparantly, French institution cannot understand the value of foreign experience whatsoever - most of the times, they won't even hire some one from another French university, so you can now imagine that your résumé is not exactly a useful sheet of paper, except in the rudest sense of the word.
You ask, then, what of the industry ?
My dear, the French industry, especially now, will never hire someone with your background. Never ever. You left the "normal" path of the engineer, now you can never come back (you sadly haven't chosen the "good path" for the longest time - especialy when you chose purposefully to go to a "petites Mines" engineering school...) Had you been from Mines de Paris, Centrale or of course Polytechnique, things might have been different, but, you know, forget about it. You'll never find a job in the French chemical industry.

That's basically what my cousin Marc's been told by his former teacher. A bleak future in a bleak environment (pun intended).

Baptiste Coulmont has told us about what happened in his field, it seems to also be the case that field also.

(Il commence à se faire tard/tôt, je finis en français)

Les laboratoires institutionnels, publics comme privés, les facultés elles-aussi, ne valorisent ni l'expérience acquise à l'étranger, ni les capacités explicites des gens. Ils restent frileux, voient moins loin que le bout de leur nez et ne pensent même pas que réserver les places à leurs anciens étudiants n'est ni plus ni moins qu'une discrimination qui va même à l'encontre de l'intérêt de leur institution. L'endogamie tue la recherche. La recherche française est endogamique. La recherche française n'a pas besoin d'un Sarkozy pour se saborder elle-même.

J'espère de tout mon cœur que ce que m'a rapporté mon cousin n'est pas vrai, ou au moins circonscrit.... je crains par expérience que ce ne soit réllement le cas. Et pas qu'en combustion !