One thing I noticed is that Utah is almost all middle class. Some have more money, some have less, but most of them are middle class.
It's relatively easy to go from poor to rich if you're really middle class. I mean that if your parents are well educated but a high school teacher and a stay-at-home-mom in a middle class neighborhood, you're poor but you can become a medical doctor almost as easily as a rich kid.
It's not so easy to become a doctor if you're raised by your high school drop out grandma because your mom's working and your dad's missing and the adults around you are unemployed, going to prison, or working at fast food restaurants. If you can lift up people in situations like that, I'd be much more impressed.
I think the Mormon welfare system is very impressive (and I do recommend that progressives take a look at it) and Utah government is vastly better than California's. But I think the lack of a real lower and upper class would make mobility look artificially better.