Two cities is not a sample, and the researcher's comparison does not lean on it as one [5]. What it offers is a pair of contrasting failure modes. Seoul's corridor received a highway removal, transit integration, cycling routes and pedestrian bridges in the same construction window as the stream [6], so the land value increase and the small-business displacement that followed [9] cannot be assigned to the daylighting by itself. Something along that corridor moved rents. The design of the study cannot tell you which part.
The arithmetic on timing is more useful than the arithmetic on cost, because timing is the only quantity the source actually pins down. Seoul's construction ran from 2003 to 2005, about two years [1]. Zürich's pilots began in the 1980s, which places them between 14 atnd 23 years ahead of Seoul's groundbreaking [2], with segments accumulating over several decades since [10]. What the longer clock buys is iteration: build a manageable site, monitor how it performs, and take the next one when a culvert replacement, sewer separation or road reconstruction opens it up [13][19]. That is a scheduling and record-keeping property of a program, not a property of a channel.
The pumps make the distinction concrete. Cheonggyecheon's channel is supplied by pumping, which is why critics have questioned its ecological integrity [8], and the project continues to incur maintenance costs [7]. Hydraulically it works. Financially it converted a capital appropriation into a permanent operating line, and that line has to be defended in budget cycles long after the ribbon. The thing this account does not tell you is how large it is: the cost is described as substantial and continuing, and the displacement as "some smaller businesses", with no figures attached to either [20].
Toronto is the cleaner diagnostic, because it has the policy without the program. The city recognizes historical watercourses and supports restoration where feasible, but that support does not say which sites come first, who assesses them, or how one gets funded and maintained [16]. Mapping is what fills that gap, and it is cheap relative to construction: culvert inventories and historical watercourse maps overlaid with flood and heat risk, social vulnerability, public land, parks and planned capital projects [14]. Its value is optionality. Once other land use decisions land on a site, daylighting there becomes difficult or impossible [15]. Flood exposure in Black Creek and Flemingdon Park already intersects with social vulnerability and limited capacity to adapt [17], which is where an equity overlay would point a first pilot [18], and it is also the stage at which resident protections are still cheap to attach [4].
