Please and Thank You

The British have a reputation for politeness in many forms, whether it’s queuing, insisting that you go first, or apologising when you bump into them. Politeness in Belgium (and I think France is quite similar in this respect) takes a rather different form.
When you enter a room, a shop, or even a lift, you will be greeted by the occupants with a “Bonjour”, and expected to respond in kind. Then there’ll be a “Bonne journée” when you leave. If someone sees you eating (even if it’s only a bar of chocolate), they will wish you “Bon appetit
Part of me admires the fact that this kind of social nicety has endured, ensuring a certain level of civilised behaviour in everyday life. On the other hand, I can’t help feeling that it’s become fossilised and codified to the extent that it’s little more than a set of verbal tics without any real feeling behind it, like when a shop assistant in the US (or, increasingly, the UK) tell you to “Have a nice day!”.
I can’t help thinking “Do you really mean that? Do you really care? Well, if not, why say it?”