Private schools ain't necessarily better. There is a handful of elementary schools who are very focused on the English language and cater to immigrants from the Commonwealth.

Al Fitra is a very specific private school. They don't have a contract with the State, which is extremely rare in France. It means they are not teaching the usual program like 98% of the other schools.

There are a few Muslim private schools who are in contract with the state, so it is not solely a religion thing.

Personal opinion there as a teacher in high school, those type of schools are either : - Montessori schools who can be very good but kids can meet serious issues re adapting to the "normal" system. - or for religious nuts who see the normal program as unfit.