I think the challenge of comparing infection and death rates is that not every country is the same. So when one country might have a death rate of 0.6%, that may only reflect potential ... (in either direction: you could aim to reduce to that or it could be how bad it could have been if you are below it).
Countries have different demographics, environment and behaviors so it's likely that the rate is going to be different between countries. Just because S.Korea's rate is 0.6% doesn't mean ours will be this high OR that low, depending on your optimism or pessimism.
But 0.6% (death rate) of 50% (estimated infection rate) of 330 million people (US population) is 1 million people.
Repeat for Europe - 2.2 million dead.
That is not insignificant and a few percentage points in the wrong direction could be even more catastrophic.