My own guess is that Baton Rouge, and to a lesser extent, Atlanta, are far more similar, culturally, to New Orleans than Houston is.
Many of them grew up in neighborhoods with extended families all around them, where their families had lived for a long time, where everybody knew everybody, and you could always count on someone for help any hour of the day or night.
Most of the people in Houston, at least the Anglos, grew up in neighborhoods where the families were nuclear and people more or less kept to themselves, socializing with co-workers and people they know from leisure activities and church and formal organizations.
Thus, when you say, that the ones in Houston were "without connections or good transportation" -- where they came from they had all the connections and transportation they needed. But it's hard for them to become Texan overnight.
Different worlds.