Yeah, the trick is that they're comparing to US World War 2 deaths when almost all the deaths from the war were elsewhere. For context, Wikipedia seems to reckon that the UK had more total WW2 deaths than the US despite being a rather smaller country, and we weren't the worst affected even within western Europe by a long shot.
The Spanish flu killed 50 million people. That’s 5% of the word population at the time. Now 50 million would barley be over half a percent.