Southland lot values

Why are Southlands lots priced much lower than other locations in Vancouver Westside? E.g. homes on double lots are priced same as single lot ones in Kits. I know it is a bit far south, zoned for houses only, but it is not that far. Marpole lots seems to be more expensive than Southlands even, sq ft by sq ft. What gives? Is it that part of it is flood plane? Is the soil bad in some way? Confused.