Their reported fatality rate.
In the most developed and transparent countries cause of death data leave a lot to be desired.
Is that because of superior health care and strong leadership, like in North Korea?
You might like to look at the life-expectancy figures for those Countries.
I'd also add that even if the absolute death weren't lower in the 3rd world, the relative death would. Being able to be freaked out about an average of .3% chance of dying of COVID if infected is a luxury that those countries struggling with malaria, rampant malnutrition, and insufficient non-COVID vaccination don't really have.
https://www.cdc.gov/coronavirus/2019-ncov/covid-data/investi...
You might like to explain why they don't, given the death-rate exponentially increases with age.