J.D.
I agree 100% as this is my approach as well.
Just out of curiosity how would you handle a business on the french side that hands you a bill (sometimes to Americans only) that is stamped service charge not included, although there is no mention of "service non compris" on the menu.(besides not going back there again). Would you just ignore it and do as you normally would, leave extra because of the stamp or talk to the management, or others..

We usually hardly carry any cash with us any way and always charge on CC. (Since they don't have any line or place for additionals on the french side)