Curious how well they were able to control for economic factors. How are they not sure it’s not “People who can afford to buy lots of coffee can also afford ot

Curious how well they were able to control for economic factors. How are they not sure it’s not “People who can afford to buy lots of coffee can also afford other lifestyle ingredients that lead to longer life, relatively.” ? Latter Day Saints and Adventists don”t drink coffee, and yet they get to brag about better than average longevity too. But that too could just be a canary for economic indicators.