All these are based on percentages of confirmed cases? It doesn't seem like they're accounting for cases that never come in and get tested, so it's probably actually lower. That's basically impossible to eatate at this point. The flu has been around long enough that they can make educated guesses.
The percentages you are seeing are coming from dashboards that are only counting confirmed cases. The dashboards are not trying to predict the final CFR, they are simply tallying the currently known CFR. This is not an estimate or a prediction for how things will turn out. It’s the epidemiologists that estimate what the real CFR might end up being, and there are plenty of data points that can help them get a decent estimate.
A big debate is how many asymptomatic/mild cases are not being counted as confirmed cases. One way to figure this out - find out the how the virus affects large groups of people that are randomly tested, where testing criteria isn’t based on a person developing symptoms. So imagine a case where 10k people were exposed to a confirmed case, and that same day we take all 10k people and start testing and monitoring. If we find 5000 confirmed cases, we check after 6-8 weeks, how many of them never develop any symptoms? How many have mild symptoms, and how many are hospitalized or die? If the rate is 80% mild/no symptoms, 20% severe/2% die, then we can apply that rate to completed cases to see how many cases we missed. If the completed numbers are showing 40% severe cases, we know we’re likely missing half the milder cases, and can adjust the CFR by half to 1.7%. But if the ratio is 25% severe cases, then we are not missing much, and the estimated CFR will only be lowered to 2.7%. (Obviously this is a simplified explanation as experts will be adjusting for age, health conditions, and other factors).
Where might we find significant testing not based on symptoms? South Korea is testing the entire church cult consisting of 210k members. We might need to be patient until all this data is ready, but regardless it’s too early to say what the final CFR will be.
One last thing - the experts provided estimates of about 8% CFR for SARS during that outbreak but, that number was actually revised upwards to 10% after everything was over. Which means the experts overestimated the amount of unconfirmed cases. When we see expert estimates of 1-3% CFR, they’re already basing that on their estimate of unconfirmed cases. No need to adjust and reduce their numbers further.