Same with places prone to radical weather. Or just anywhere that doesn't get a lot of sun (the farther you get from the equator, really).
Because even if we get solar panel cost down in the next few years, it is still going to be expensive and need a fair amount of maintenance. And if that doesn't offset the cost sufficiently, it isn't worth it
Believe me, I want clean energy and do think solar should be exploited where it is reasonable (same with wind) and wish we would at least use cleaner sources where it isn't. But studies/experiments like this tend to rely on best case scenarios and corner cases and often just don't take economics into consideration.
Are they good as proof of concepts and PR? Yeah. But they still aren't that representative.