Fiscality has never stopped anyone starting things. Issues actually appear on the long run only.
Comparing US versus UK versus FR is a non-sense if your ambitions are global. You can start anything in France. Money is cheap, Engineers 3x less expensive than UK or US. And there are plenty of people unemployed looking for a great purpose. It's a wonderful play-field for someone ambitious.
France is 38th on the list, UK is 10th and the US is 4th for "ease of starting up"
I am not sure engineers are 3x cheaper in France. Don't forget that the cost of employment (and unemployment) are horrendous for businesses.
Don't get me wrong, I know plenty of entrepreneurs in France. They are very talented, full of ambition and hard working but they all say it is very hard. There is also a complex in France with money and success but that is another debate.
Nobody said it is easy but it definitely helps if you live in an entrepreneur friendly country, because you will meet people like you and start things quicker.
France offers a tremendous amount of help to start, cost of employment is not worse than any other developed country (yes there are a lot of taxes, but salaries are lower because a lot of stuff is provided by the state) and mentalities are evolving towards a more startup-friendly attitude.
The only problem of France are French people who don't believe in their own country.
I agree with you that there is a trade-off with social advantages. NHS is not as good as having a carte Vitale but I still prefer to live in London.