Your last paragraph perfectly describes why as a French speaking American engineer I refuse to work in France even though I would love to live there. My salary in a flyover state in the US is 5X the best I could find in France.
Part of the problem is trying to employ people in France or, more specifically, worrying about the day when you need to stop employing someone in France.
After going through it once, I'll never voluntarily do it again.
Germany is also an issue. At a previous job, we completely moved all development work from Munich to Dublin because the added headaches caused by hiring/firing in Germany were enormous.
Our story is similar, though we've chosen other employer-reasonable locations. Netherlands was moderately bad (better than France, though); Switzerland is reasonable.
Do France and Germany have the concept of the "contractor" worker, where the company can just call the contracting firm and say we don't need the developer anymore?
I agree that developers in France are rather underpaid, but you're comparing apples to oranges.
A lower French salary comes with a number of valuable benefits which makes the take-home pay difference much smaller than what you're saying : https://news.ycombinator.com/item?id=13412599
