The reason why in France waiters aren't tipped but cabbies are (10%) is that waiters are well-paid here. Their salaries allow them to support their families on so they don't need or expect a tip. Being a waiter is a lifelong profession, not a stopgap job while somebody looks for a 'better' job. Each single item's price on every menu has built into it a sum for 'service' which goes towards paying waiters' salaries. Some waiters feel insulted by foreigners who assume that waiters must rank so low socially that they'd need charity! Many waiters have earned diplomas at colleges. (So have bartenders, different categories of cooks increasingly, hotel receptionists and other professions in the hospitality industry. An important new school for certification in about 10 such fields opened in Cannes 2 years ago.)
A few months ago at one of the cafes we frequent most, an American guy next to us went into his wallet to get a tip out after he'd paid his bill. He looked uncertain about how much to give. I sometimes tell Americans the score here on tipping. I started doing that a year ago when an American diner at a resto - a cruise line employee - asked me just how much one was supposed to tip in France. She'd gone broke leaving 20% everywhere for her and her daughter over 3 days and this was their final meal before leaving the city. This was her third stay here. She appreciated my help once she believed me! I felt bad that she hadn't known earlier when it would have saved her a lot.
But when I later helped that American at the café this way, he looked in the opposite direction to me (never done here because showing basic respect in public is a social obligation) and said, "But look at how bad the state of your French economy is! The waiter needs a tip." His rudeness shocked me. (The waiter dresses well, is young and is groomed like they all are.) The waiter saw and caught that arrogance said in English and my consternation. After that glum-faced smartass and his embarrassed wife left, the waiter (a funny guy) refilled our glasses for free and said in French, 'There! -we're all poor!". (I'm not French but live here.) Free tidbits etc at restos are rare here, especially compared to BA.
I have great American friends, really nice people. Nonetheless, it just happened that I've stopped offering Ameican visitors here help since then. I bite my lip when I'm about to and then say nothing.
Regulated cabbies here aren't paid some regular salary. Driving a cab isn't a certified trade although cabbies are licensed. What money they make varies. Also, their cab plates (medallions) cost them a fortune as these do everywhere they're issued. That bred the public's empathy and cabbies require a tip. They're always as appreciative as BA cabbies are of a tip although here one is required and in BA it's not.