You can always gauge the happiness level of a country when you step into one of their taxis. "'Ello love" is the genuine greeting from any London cabbie who then natters about the weather and thrusts the Currant Bun/Sun in your hands. You'd be lucky with a grunt in Paris.
It's like that old saying - if you find yourself outside in your pajamas in the rain with a tube of super glue in your hand staring maniacally at damaged road furniture, that's the first sign of madness.
Coming from a country where people are generally a bit more chatty (no blarney stone references please), I've found it odd not saying hello to people when I enter a shop, though I am now accustomed to the ensuing look of panic if I smile at someone on the tube.