Not true for SK. In addition to aggressively tracking down and testing anyone associated with any person who tested positive, they are randomly testing large numbers of non-symptomatic people, and have set up test stations where anyone can be tested for free and get results the next day. Over 200,000 tests. 200,000 tests goes way beyond "statistically significant. If there were large numbers of "unreported" cases, they would show up in these tests. For most other countries, your argument is almost certainly true, but not for SK. Also, asymptomatic cases are mostly a myth, and are actually "pre-symptomatic" cases found through contact tracking. Actual asymptomatic cases are about 1.2% according to the WHO.
SK has 50M people. 41M urban. is 200K enough?
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