Without a college degree, life in America is staggeringly shorter

I always wonder how much these differences are just a function of wealth + connections starting at a young age.

Early childhood education and socialization has a dramatic impact on effective literacy, numeracy and mathematical skill (essential for intuitively understanding finances), social ability, etc. The effects are lifelong. Wealthy people, as a group, have more resources that make early childhood productive for their children. The typical wealthy person lives in a community with a good school, may have a private tutor, and probably has more time to spend with their kid. A person raised in such an environment could easily develop the skills to succeed with or without a college degree; but college is a predictor of even more resources, and it's relatively less of a burden for wealthier people, so that's where they're more likely to go.

There's a point in adults where learning something like algebra (essential for financial literacy) realistically isn't going to happen. It can, it just won't. And it's consistently those adults who struggle to adapt to our world of numbers and financial instruments. Lacking access to resources locked behind walls of numeracy and advanced reading comprehension, less educated people are simply not going to flourish. While it's always possible to redesign parts of an entrenched system to empower disadvantaged adults, it's more effective and efficient in the long-term to address the issues at their roots, which generally means better educational and social resources for children.

Not to discount the importance of labor unions, worker protections, etc. for adults. But focusing on college degrees by themselves gives us an incomplete view of things.

jarring difference in decline post covid

Different levels of trust in institutions is probably part of it, but I don't think it's even that complicated. People without college degrees are more likely to hold jobs which can't be done remotely. Before the vaccines were available, that meant more exposure to what was a relatively mortal disease. Thus more of them died, and their life expectancy as a group went down.

Lower-income people, including those without a college degree, are statistically more likely to engage in behaviors like smoking. They're less likely to have a good diet. They probably live in a more polluted area, and don't necessarily have the time or inclination to exercise. Like the article says, drug abuse is also more common. All of those things makes them especially susceptible to disease in general, and this one in particular. Ignoring calls to get vaccinated surely accounts for some of the drop in 2020, but the risk factors mentioned here aren't specifically related to trust in institutions; rather, they reflect the day-to-day behaviors that people without resources are encouraged or forced to engage in.