If you just offer it, people can say yes or no, whereas if you tell them they have to have a minimum knowledge of French...
This also affects the entire matter of safety, which is a major concern to me. I've seen flight attendants going quickly down the rows and telling people to buckle their seat belts in English, but the person seated next to me asked me what the flight attendant had said.
This is extremely dangerous from a safety standpoint. Work really has to be done because you could have serious problems at Air Canada as a result of communication. You don't always have time to switch on the little bilingual recording when things start to shake in the aircraft. Sometimes it doesn't even work. So if your staff isn't perfectly bilingual and can't speak to people quickly—