Why does CVS open right across from Walgreens? And Autozone right across from O'Reilly?

Question

I've noticed something odd. Everywhere in the area that has a Walgreens...a CVS opens right across the street!!! Everywhere that there is an O'Reilly Auto Parts... an Autozone opens right across the street! This seems to go against common sense in that you would want to open a store in an area not being served. I don't mean it seems this way, I mean RIGHT ACROSS THE STREET literally! Is there something going on with these companies?

Answer 1

I noticed too. In my town we had a brand new CVS built a few years ago. Now Walgreens has bought the area across the street and they had to buy out a DQ, office strip, and a lodge. Just to have that space. CRAZY!! and our new auto zone was built across the street from the new O'Reillys , they were built a few years ago too.  

Answer 2

I used to wonder the same thing but when it all boils down to it : Competition. People like choices and options. I know if I don't like the help at one store, or one store doesn't have what I'm looking for, I go to the nearest option possible.