Going by wikipedia's stats, bulgaria is noticably richer at PPP, but not in raw $, so it's not surprising you'd notice the difference in person (and I'll bet the region you visited matters too). The inequality will matter too, as you say. Brainfart about serbia, I was simply skimming european countries ;-).

Ref:

- https://en.wikipedia.org/wiki/List_of_countries_by_GDP_(nomi...

- https://en.wikipedia.org/wiki/List_of_countries_by_GDP_(PPP)...

- https://en.wikipedia.org/wiki/List_of_countries_by_income_eq...