The article (and your comment) explains how the design conforms to the constraints but what I think they were asking was why have those specific constraints in

The article (and your comment) explains how the design conforms to the constraints but what I think they were asking was why have those specific constraints in the first place (apart from "that's how it's always been done here.") Now, I understand that it's to prevent accidents, make it more easy to put mail into mailboxes if they're situated right next to the road, etc. Yet somehow every other country makes it work without specialized vehicles.