White Roofs? Too simple?

In a post title Geoengineering Done Calmly, Matthew Yglesias wonders:

That said, trying to get people to paint roofs white seems like a total no-brainer and given how solid the science behind this is I don't really understand why there isn't more momentum behind it.

My surmise is that white roofs are too simple a measure. No joke. People seem to like complexity and novelty when it comes to solutions. 'Green roofs' — vegetated roofs — get a lot more attention than do white roofs. White roofs are a proven, existing technology with precise costs and benefits. Green roofs are speculative, experimental,and of uncertain benefits. On which one do you think the public and media want to focus? Of course, the green roof.

Do you detect a note of skepticism? Well I confess it's true. To me, the idea of keeping water on a roof grates like chalk on a blackboard. But then again I have been wrong before; and green roofs are certainly gorgeous — no question — to the extent one can see them. I am just waiting to see the facts from real installations over a period of years.