I quite well comprehend that richer nations have better testing. Those are the test results we have to go on (not Cameroon or North Korea - those would be blank guesses). The numbers are static across all nations that did serious population testing, so we actually do know the asymptomatic rates, and they are not 5x the diagnosed rates. They may well be 5x the positivity rate in poor countries that don't do much testing, but that still doesn't change the asymptomatic rate for people who have the virus.
Second point: Hospitals were recording symptoms of covid even prior to widely available testing, and as soon as the virus spiked their ICU beds were full. This has been the case in every country in the world. They didn't need to test patients. Those patients were dying in the hallway, and on ventilators. The spike was clear and obvious in each country when it arrived.
And in each country, the percentage of people testing positive who had no symptoms was roughly the same. So the argument that there have been 5x as many people as reported who had covid - and had no symptoms - is totally false.
Actual infections 5x the number of cases detected through testing in rich, developed countries with relatively widespread tests seems pretty plausible, I think there's some evidence the UK was close to that despite testing pretty heavily compared to the rest of the world e.g. https://www.news-medical.net/news/20210215/Only-2525-of-SARS... (I seem to recall the BBC reported on this at the time, but finding their old Covid-19 coverage again is basically impossible.)
Remember, fully asymptomatic infections aren't the only problem, there are also infections that technically have symptoms but they're too vague, commonplace and non-specific to lead to people getting tested.
Second point: Hospitals were recording symptoms of covid even prior to widely available testing, and as soon as the virus spiked their ICU beds were full. This has been the case in every country in the world. They didn't need to test patients. Those patients were dying in the hallway, and on ventilators. The spike was clear and obvious in each country when it arrived.
And in each country, the percentage of people testing positive who had no symptoms was roughly the same. So the argument that there have been 5x as many people as reported who had covid - and had no symptoms - is totally false.