In France taxes are just applied differently, but the taxes you pay at the end of the year are almost the same. Also, the total of the salary of a CC is made differently in differnt airlines/countries. In some airlines what makes the difference is allowances, in others flight hours, or bar sales, that are all taxed differently.
The reason why so many choose to live overseas is that the cost of living and renting is much cheaper.
No, if you lived in France and worked for a French airline you would pay tax.
If you live in France but work for British Airways you pay almost no tax.