The null hypothesis is that the differences in death rates between countries are mostly a matter of luck and timing rather than caused by pandemic control measures (or lack thereof). Only a few countries have successfully contained the virus: mainly New Zealand, Vietnam, and possibly Taiwan, China, and Australia. For other countries which still have widespread community transmission we may see the per capita death rates gradually converge (after adjusting for population demographics).

To be clear I'm not claiming that all pandemic control measures are ineffective. We just don't have strong scientific evidence that they are effective at the national level over long periods. Sometimes things just happen randomly. Is it possible that Sweden just flipped the coin to heads a bunch of times in al row and now it finally came up tails?