Monorails are still used as a part of "subway" systems around the world, but (from what I heard) they usually have less capacity than regular railways, so most

Monorails are still used as a part of "subway" systems around the world, but (from what I heard) they usually have less capacity than regular railways, so most big cities end up building conventional subway system. Also, it turns out residents and shop owners hate a gigantic elevated structure that blocks sunlight half of the day.