Mwah, that depends on what you consider walking distance. I remember walking back from a Rite-Aid in SF when attending an IETF conference, entering the conference hotel and being asked by other attendees 'where the hell I managed to find a Rite-Aid here'? Well, it may have been a 1.5 km walk but it was there, sure enough. I did not look it up beforehand, just started walking out of the centre and found one. Sure, if you only look in the local block you won't find one but then again if I walk 1.5 km from where I live I only find more trees so everything is relative.