Their testing rate is only a bit above the US rate and is lower than Victoria's.Utah That's one of the youngest populations in the country. It's a young non-drinking non-smoking healthy population. overall more affluent than much of the other country with lots of healthcare access. They also tested a lot and therefore intervened on cases earlier than places that wait until only the sickest arrive already on the downhill.
But you are probably right that health and age explains it. We have had mass outbreaks at aged care facilities, but I assumed Utah would have those as well considering overall having a much higher amount of cases.