Because no business or appointment is ever that urgent in St Petersburg. Because nothing could ever be that urgent compared with the prospect of a bottle of portwine shared with a friend or acquaintance in a mid-afternoon dvor, or a malinki dvoinoi (small double-strength coffee) in Saigon(1). Because no true Petersburger could walk, or run, or crawl, five metres on Nevsky Prospekt without receiving at least three invitations to coffee or portwine on the way. Because Nevsky Prospekt is deceptive: it appears, on the map, to run straight, true as a railway line, from Dvortsovaya Ploshad to Ploshad Vostaniya; yet when the Petersburger sets foot on it, it turns crooked as a country lane - weaving this way and that across the city, spilling drunkenly into cross-avenues, allowing itself to be lengthily detained in hidden courtyards, pulling over at crossroads for a quick word with sleepy side-streets - in fact, all but losing its way altogether.
There is, of course, one very simple method by which the Petersburger could speed up his journey: he could take the metro. Maybe, if he ran, he could make the three-minute trip in little more than an hour and a quarter. But then he would meet fewer of his friends and acquaintances. He would visit fewer dvori. And he would drink significantly less portwine. In many respects he would cease to be a Petersburger at all.