I actually doubt it has to due with the income level of the area. I think it has to do with Safeway's staffing model.

I go to a Tom Thumb occasionally in a nice neighborhood. At best they have 1 checker open, they never have the express line open, and they seem to want to force everyone (even if you have a full basket of groceries) to use their self-checkout model. So I only go if I need 1 or 2 things.

Appears to me that corporate store operations is trying to cut costs by trimming labor. Could be wrong, but I'll bet a bunch that I'm right.