Personally, I think 5 is too young to be cycling in an urban setting without adult supervision, and that's nothing to do with paranoid Britishness: I know far too many adults who have been knocked off their bikes.
Walking is different, safer, more control.
And fwiw- it's not only Continentals in idyllic rural settings who let their children walk to school. My Swedish family live in a city that is twice the size of the one we live in here in England, there are cars, there are main roads, all the hazards of modern life- yet children have far more freedom.
My dh grew up in London, which was certainly a lot more dangerous 30 years ago than our own smaller city is now.
Yet there seems to be this perception that everywhere has to be more dangerous these days, by mere virtue of being 30 years later, or not on the Continent.