I definitely notice that on the whole, most of the language I hear from less-educated families is directive around the child's behavior, while the language the more-educated families use involves more questions and is more focused on concepts. The point of the article was of course how less-educated families can make some fairly straightforward changes that can narrow the achievement gap, but I also thought there were some implications that more-affluent families are doing things entirely right, which I don't experience as accurate.
While I have definitely worked with a lot of less-educated families where I feel as if the child is only spoken to if doing something wrong (and often in a vague "be nice" or "don't do that" sort of way that doesn't actually teach language or behavior), I also see more-educated families who don't seem to ever direct behavior. In some cases this seems to cause patterns that look a lot like AD/HD or PDD, where the child can talk at length about various subjects, but doesn't know what "sit down" means or that following directions is obligatory. It seems to me that some moderation here would be ideal, where adults are asking questions and talking to the child about their world, but are also saying "no" at appropriate times and giving directions and expecting them to be followed.
In terms of books, there seem to be developmentally appropriate and inappropriate tactics I see from all sorts of families that don't seem to be related to class or education. Some of the families I work with only read the book cover-to-cover without doing any pointing to pictures, labeling, asking questions, showing the child how to point, or even letting the child touch the book. Many insist on using the exact words/concepts printed in the book even if they're not developmentally appropriate for the child, like saying "cardinal" instead of "bird" because that's how the book has labeled the picture, or talking at length about how "things on this page are red" instead of labeling them for a child who doesn't yet have a lot of words and isn't anywhere near colors. Others seem too focused on being open-ended and exploratory and might be physically present and making interested sorts of faces and noises, but the child seems to only know how to flip rapid-fire through the pages, or scratch at one page, and the parent isn't guiding the child at all. Again, moderation seems to be the key.