If you are male, your life will probably be wrecked at some point by a heart attack/stroke or prostate/bowel cancer. The risk of cardiovascular disease can be reduced in various ways. You also might have rarer but more significant risk factors for premature death from cardiovascular disease (eg Lp(a)). There is still an unacceptably high rate of death or severe disability from the primary cardiovascular event ie. you don't get a second chance, as the first sign of the disease can be fatal or disable you permanently. The screening tests one has in an annual checkup are not 'extensive' really, it is asking questions about lifestyle and family history, checking lipids, routine bloods, blood pressure and doing cancer screening after certain ages. The chance of an incidental finding resulting in harm is very low with this kind of thing.

Has a proactive, annual checkup model been properly compared to doing nothing on a population level? No. But on an individual level, it makes a lot of sense.

I would say it is not useful to compare mortality rates between countries. Norway has the highest GDP per capita anywhere for example, and is quite culuturally, geographically and genetically homogeneous. How would you make a useful comparison to the USA?