The US has good emergency healthcare. If you go to the hospital with a SpO2 under 90 and not a cent in your pocket, you're going to get treatment.
Obesity is not the only risk factor in the epidemic, nor would I argue is it the primary one.
The US is in the top 10 of all countries for deaths/capita. That's not doing well. If you ask why some places in Europe did worse, that's a good question. There are a lot of variables included density, weather, mitigation measures, etc that are going to be hard to unravel.
The UK has dealt repeatedly with it's own strains of denialism for the whole year. It's not just a Trump-specific thing.
Lastly, South Dakota and Mississippi, two quite rural states have some of the worst COVID death rates in the USA. Compare with, say, Vermont.