Scott isn't exactly known as a schmoozer, so him not having an oscar makes perfect sense in a way. I doubt that Washington is naive enough to think these awards are completely about how good someone's directing is (or that such a thing can be meaningfully defined and compared).
No. But you can get a lifetime achievement Oscar, which is as close as it gets to retroactive. But also, it's an industry award, they are more about connectivity than merit, and if you look at the data on a long scale, the academy is REALLY good at giving Oscar's to films that are very well made, but didn't quite blow up, to get a little extra juice to the bottomline.