Relax, no need to become agitated or defensive.
Sure, a person can just be nice. It happens a lot. I also find it interesting that a specific type of person in a specific area, which has a well-documented history of deadly oppression against that type of person, is unfailingly cordial to me, identified by sight as a possible representative of the local oppressor type, in stranger-oriented situations; while other types of people in that same area are not, and while the same type of person in other areas are also not.
I suppose that that specific type of person in that specific area could simply just happen to be, as a group, far more cordial (or "nice", if you prefer) than the other types I mentioned. It's possible, but I find that a little far-fetched when taken against the other, to me more probable, explanation: that the history of deadly behavior toward that type of person precipitated a necessary survival strategy of highly-visible, inordinate, even excessive cordiality as a way of gaining enough approval in the moment to survive the encounter. This is consistent with the voluminous historical documentation of the subject, it was a very real circumstance well past the mid-point of the last century, and it makes more sense than the explanation that, by simple coincidence, this group of people in this specific area just happen to be far, far nicer (i.e., more cordial) than any other group of people in any other area I have encountered.