I know that there's people who are at least 100 years old or above in Japan, as their life expectancy is higher. The shortest answer is diet & portion sizes: since Japanese cuisine consists of seafood, rice, soybeans, and seasonal vegetables. Most portion sizes are controlled and turn out being smaller with a cultural practice of 腹八分 (はらはちぶん) or eat until about 80% full. (They opt for cold, green or hot tea rather than sodas).

There's universal health care coverage in Japan at least while in USA people stress about medical bills a lot. Exercise is incentivized in Japan via active movement (not as car dependent) from walking, cycling, and using stairs are built into everyday routines keeping people mobile into old age. That's the opposite of US since they're heavily dependent on "the car" as opposed to public transit, bicycles or walking on foot.

Because health care makes us go bankrupt.

It's not that simple. People seem to be so focused on just the diet they forget about the bigger picture. Starting from healthcare, which is notoriously bad in the US, all the way to community, which studies have shown to be directly related to improved health (again, weaker in the US, stronger in Japan).

Even if just focusing on the diet, two people in the US and in Japan could have the exact same diet yet have different health outcomes, due to the poorer food quality and safety standards in the US (not even gonna go into food deserts and pollution which are a whole other thing).

The Standard American Diet, for one.

The other major factor is the government's need for "productivity" to constantly increase.

Any new technologies aren't used to make workers' jobs easier; They're used to get more work from workers, so stress levels keep pushing the limits of human endurance.

Lifestyle is another factor. Japanese people walk a lot more, living in neighborhoods where they can go shopping, socialize etc all on foot. An elderly American living in the suburbs who has bad eyes and can't drive anymore will be mostly stuck at home, contributing to the deterioration of their health. Japan also has universal public healthcare, so dying from being unable to afford treatment is not really a thing. There's also a strong culture of respecting and providing assistance to elders which I'm sure plays a role as well.

Look at the best performing countries re. Life expectancy. The actual shortest answer is accessible healthcare.

https://www.worldometers.info/demographics/life-expectancy/

If my understanding is accurate... mostly healthcare accessibility

Japanese foods aren't as healthy as most ppl would imagine, there are lots of fried stuff and high-salt stuff. And wealthier subsections of American cities can have life expectancy values hit close to 90 (see this Chicago map for example, the Loop has sub-parts where I was told life expectancy goes 90+)...

Also a side note, the 100+ observation might also be biased by bad data collection. See this primer/summary by The Guardian. The "Blue Zones" in Japan which have tons of super-centenarians tend to be in poorer areas which were bombed during WW2 and lost birth records

A few researchers have found that blue zones, i.e. regions with a higher proportion of people above 100, was primarily caused by to poor government records and pension fraud. This was found in Italy, Greece, and Japan. Lots of faulty assumptions were made about diets and propagated widely.

not so much pension fraud

https://allthatsinteresting.com/blue-zones-supercentenarians

The new study found that longevity claims in blue zones, or regions famous for long lifespans, are largely based on clerical errors and pension fraud