While here in Australia the local dealers seem to sell a strange array of leisure bikes with bewildering geometry, suspension forks and the kind of cheap and complex running gear that requires but does not reward maintenance, in Asia almost every bike you see is a single speed.
Many of the bikes have classic step-through triangle-frame design and are made from steel. There’s some strange shapes there though, with single spar frames being quite popular. The locals buy these bikes for the equivalent of $100-200 brand new. For that money you get a rear drum brake and a rack. The rear carry rack is enormously important because it is where your passenger sits. From there the passenger has easy access to the pedals and can help climb hills.
Even the cyclos puff away on one gear as they haul fat tourists, their two fat children and full luggage from hotel to watering hole.
There are millions of single speeds in Asia because they’re cheap and reliable.