Simplification & Science
I would argue that for questions about the color of the sky, it's enough for the non-scientist to know that it has to do with the way air scatters different wavelengths of light. Incidentally, I agree with commenters there that the color of the sky might not really be one of the most important science questions of today, but it's included because it is a frequent wondering (in fact, some of my 7th graders are presenting on this very topic next week). Other questions are there because they lead to more questions or startle... I think that's behind the question about the percentage of the earth's surface covered in water - it's such a large number, it might make some people reconsider the importance of understanding the oceans. Some questions (such as the salt on roads) are there because they have practical relevance. And other questions are there because they are important for scientific literacy, necessary for making wise decisions as a citizen. Evolution comes to mind, as does the question about bacteria and viruses. I think everyone needs a solid understanding of evolution and natural selection, and the role that plays in how we fight diseases is important (genetically modified food and anti-bacterial soap, anyone?). The non-scientist needs to know enough to be able to learn more when interested and to evaluate information encountered in the media; that's not the same level of detail or precision required of a working scientist, obviously!
What science questions do you think all students should be able to answer at high school graduation? (And for that matter, what history questions? What math questions? What literature questions?)