You are pretty much right one Louise! In France the service charge when included in the prices labeled on the menu is not "redistributated" to the staff.. It only helps the restaurantor to pay the staff's fix salary at the end of the month, which is why a vast majority of the restaurant include the service (service compris) in their prices... Contrary to most American people are convinced, te waiters are not super well paid in France! I always read this line " yeap but in oposit as in the States where a waiter has a very low wage and survive on tips, the french waiter is much more and better paid..." A waiter usually earn the minimal legal wage of approximatly $8 an hour and cannot work under French Law more than 35 hours per week!!! Make the calculation and you'll see that his salary is not super great! Of course beside their salary, like all French people they have some benefit.. 5 to 6 week paid vacation, Socialised medecine, Retirement, unemployement insurance, etc....
On the other hand a restaurantor who chose not to include the service in its prices and will label "service non compris" takes full charge of the responsability of paying the staff's fix salary without the help of the "customer" and taking the "hit" on its margin of profit, which is more rare to see.
When a customer leave a "tips" (pourboire) on the table, this will go directly to the wait staff.. now, every staff team has a different way to redistribute it within their group... sometime each waiter is responsible for its own tips (pourboire) and keep the full amount, sometime he will share a 5 or 10% with the bartender, and sometime the tips goes in a basket and at the end of the service it is share within the waiters at equal share... it's all depends hwo they decide. But in any case, the restaurantor shouldn't touch it.. I know that unfortunatly it is not always the case and I could name few of them in St Martin who take their share on the staff tips, if not taking it all and give only $1 per customer for to each waiter!!!... you have dishonest people everywhere unfortunatly...