The idea behind Vancouver's decision is that, despite being of a more vintage grade than levers, doorknobs kind of suck. Ergonomics studies investigating different types of water-dispersing mechanisms have shown that lever-style faucets are far preferable to their knob counterparts. (Yes, there are studies for everything.) Knobs, you see, involve pronating and supinating your wrist, (stretching it, basically) which is less fun for everyone, but probably won't make you run out and immediately switch to levers. Maybe you like your nice art deco knobs.