You may notice that Walgreens is always on the corner- in fact, a lot of major corners in every large to small metropolitan area- and often within eyeball distance to their main competitor- CVS.
Convenience is my only motivation to shop there, as I am often willing to forego discount prices elsewhere for the convenience of being able to drive only a few blocks to get what I need or want.
Walgreens drive-through pharmacy is also convenient, and better for me than having to walk-in just for a prescription, after having dental surgery and still bleeding or slobbering all over myself in public.