Is it fair to compare a book on only 15 issues to one with nearly 50? A lot of the characters in Scalped remained pretty undeveloped for a long time, like Shunka for example, until his 2-issue arc, he seemed like a generic heavy, but then we found out thathe's gay and explore all the issues surrounding that, and suddenly he's a whole new character. It's the same with Nitz, and Catcher. I'm not saying AV will definitely become as nuanced and deep as Scalped, because very few comics are, but it may do so in time, or at least become deeper than it is.
In Casino Boogie, the second arc, Aaron was already focusing on minor characters. A significant part of that arc focused on Dino Poor Bear. The first 10 issues of Scalped had tremendous character development and set the tone for the rest of the series.