Simple - people don't want to live in those states as much as California. For example, we have palm trees in California. They have them in Florida too - it's not the same!
Similarly, Texas also has nice weather but it's way more variable than California which has a fairly temperate climate. In TX crazy temperature swings are the norm. Also, I've known a number of Texans throughout my time in the Bay Area, pretty much all of them from Austin. The culture of Austin is the most like California and San Francisco - artsy, liberal, etc. Places like Dallas, Fort Worth and San Antonio are decidedly not like San Francisco.
To your point about Prop 13, I agree that it's an issue, and it's definitely a major part of why we keep having this budget crisis over and over and over again, every friggin' year. Sadly, I don't think Prop 13 will be abolished or really revised until the state is completely broke - much worse than it is now. But eventually it will change.
It's more complicated than that. Prop 13, cities forcing a lack of density and other polices and forces I don't know about push California to it's sky high rates.