Do you even understand how your schools are funded? You might not pay the same for school, but in return you will have a much bigger percentage of your future paychecks cut off in taxes.
If you and X from America has the exact same job and degree he will be able to cop twice as many raw jeans and drive a better car than you.
Public universities are funded by the State. But they have an autonomous status, so they can be funded by private organisations if they desire so. I'd like to add that registration fees depend on you social status and revenues of your parents.
As for the "civil service" schools, who train you to be judge, teacher, prefect or whatever, they are part of the State.
This system is relevant and very efficient.
As for your second part, concerning the salaries, LOL. France have the best economics managements politics and sciences schools of the world with US and Japan : HEC, EM LYON, ESSEC, POLYTECHNIQUE, SCIENCES PO and l'ENA.
So its not that much a problem for a student from those schools to left France and join the US. (it does happen when you've just postgraduated. We often start in foreign countries then come back to France).
And finally, France society and all its benefits, like security (compared to the US, its much much much safer), we have a good healthcare, very equal and efficient publics services and etc...
So, you see, Id rather pay my revenues taxes in France.
Oh and yes, first incomes after MA in France are : 38 000 euros per year. So basically, at 24, 25 , i'll be able to cop 1 000 raw denims if I want. But thats not the point, and its ridiculous.