I use to work for AAP and I can tell you first hand that the commercial department, that is the department that deals with shops and local business, is what keeps the majority of those stores afloat. Also, I agree with what most have posted here. 80% of people who walk in those doors need the part the same day to be able to get to work the next day. They have brick and mortar stores for the convenience of being able to get the part(s) the same day and the old saying of 'convenience costs' is very true.