Low salaries should help the startup scene, not hurt it. Where would you rather create your startup - somewhere where it would cost more to hire or less?
Lots of talented people end up working in another country, especially top talent. Would you rather have a glass ceiling at 40k or start at 100+k in SF?
Not to mention, low salaries garantees that not much international talent will relocate in France
France is full of "service" jobs, those are crap and lower the average. Just ignore those and look at the jobs that matter, if you're the kind of developer who would have the skills to relocate to SF.
If you're senior, in France, you can get a fairly good salary as a developer. There is definitely no glass ceiling at 40k; you can get more than 50k easily, and above 70k if you have can find the right company with a good fit.
Comparison with SF is hard because it's such a weird place in terms of housing, US healthcare etc. So if you compare to Germany or UK, you still make less in France, but the gap is much smaller than 10 years ago and it's still contracting.
That started before Macron actually. You can find jobs in well-funded startups (instead of the starving startups of 10 years ago happy to raise a million), and more and more international companies (US and others) are now recruiting engineers in France.
I don't know about that... Salaries in the UK are crap, much lower than in the EU; and I have the impression that London is only up in the stats because of the quant jobs, which while technically 'software development' jobs, are out of reach for most people that would consider themselves 'software developers'. Now I don't keep quite as close an eye on the UK job market as I used to, but even the job opening and contracts I see on mailing lists I'm on, don't make me want to jump ship...
That's only true if you don't lose capable talent due to the low salaries. If most of the talented French engineers move to Germany to get higher pay, then the low pay will hinder the startup scene.
Not to mention, low salaries garantees that not much international talent will relocate in France