I cannot help noticing that her obituary mentions she was a great photographer, nonetheless a few days after her deaths her relatives were immediately giving away all her work by the kilogram. It makes me think how lonely photographers are in their passion. Most people would not understand taking pictures of anything different than their relatives, dog, girl-friend, and places they were during holidays. Nothing wrong with that, but I think that for most people taking simply pictures of "life around us" must seem weird, the hobby of the nut. No wonder she was not "understood" in life. She probably had no understanding, appreciation and no encouragement from people near her.
Another thought: some of the pictures of Vivian Maier are, so to speak, "obviously good". Nonetheless she probably had no illusions that a nanny could ever walk into a gallery and propose her work. If she had been friend with some famous photographer or gallerist of the times she could maybe have been famous. The point here is that "obviously good" images maybe are not enough.
The "great photographers" we know are probably just a random selection among the many equally great unknown photographers around us. The "random" selection is mostly made by life circumstances that end up being more important than the body of work itself.
Or maybe not. Vivian Maier left behind her a huge body of work. It's likely that the vast majority of those images are not that interesting anyway. The first rule in this case should be: "show only the best". And one has to be able to discern what is better and what is worse. And she wasn't a good printer, it seems. Well, that reminds me of an aunt of mine, which writes absolutely stunning poems in Roman dialects but lacks the "energy" to do all the limae labor, the painful job of perfecting the raw material to make it shine. She finds "instant satisfaction" in the poem as it first appeared, and than just concentrate on the next one. She doesn't even see when a verse is somehow weak, or when there is some style problem. I suppose Vivian Maier was a bit the same: more, more and more pictures, without too much self-critique, without the urge to perfect the art or printing. "Instant satisfaction" without a "direction" so to speak.
It's perfectly legitimate, it's her choice, but it's also a pity because this way a lot of genius gets wasted in the world.