The same is true for the flu. People get it every year but they don’t go and get swabbed.
I also agree that there’s a wide range of possibility. But I’m responding to the claim there’s no data with a study from China’s CDC that most experts are citing as the best info we have right now. Is it perfect? No. But the Diamond Princess isn’t a scientific study — it’s a mess.
Edit: for a range of possible outcomes, this article is helpful:
https://www.forbes.com/sites/kenrapoza/2020/02/25/coronaviru...
At the low end are South Korea’s (mortality) numbers, at the extreme high Iran, and Italy aligning roughly with China’s study.
The tl;dr is we have a fairly wide range of possible outcomes, but Italy is lining up with China’s findings.