Much like Korea, Japan, and other advanced countries, Taiwan has a land value tax which requires it to monitor land value regularly. And they do, apparently pretty well, as indicated by this report that 2011 land values average 8.65% over the previous year. The land value tax could be one of the reasons Taiwan seems to be more prosperous than most countries, but that isn’t my point.
My point is that assessing land value is not exceedingly difficult, if one has competent and reasonably honest assessors. The most valuable land in Taiwan is reportedly under the Shin Kong Life Tower, NT$1.21 million per square meter (about $4,000 per square foot, a figure probably never seen in Chicago).
Thanks to the Facebook LVT group for the link.