It's true that trying to consider the mild cases would depend on more testing. Assuming actual deaths are more accurate than the death rate, perhaps a more reliable way of assessing a country's damage would be to look at coronavirus deaths versus population:
China 1.386B / 3070 deaths: One in every 415,465 people died
South Korea 51.47M / 48 deaths: One in every 1,072,291
Iran 81.16M / 145 deaths: 1 in 559,724
Italy 60.48M / 197 deaths: 1 in 307,000
Spain 46.66M / 10 deaths: 1 in 4,666,000
Switzerland 8.57M / 1 death: 1 in 8,570,000
Japan 126.8M / 6 deaths: 1 in 21,133,333
France 66.99M / 11 deaths: 1 in 6,090,000
United States 327.2M / 17 deaths: 1 in 19,247,058
The first cases of coronovirus for South Korea and the US were January 20th and 21st, respectively.
Adjusted for population, the US has had one-eighteenth the deaths of South Korea due to the virus as of March 7th. Or to put it another way, the Trump administration has been 18 times more effective, so far, in containing the virus than South Korea has, but admittedly only 3 times more effective than France.