Theory suggests that individuals are more willing to sustain personal costs to benefit ingroup members compared to outgroup members. Real-world tests of parochial attitudes have lagged behind decision-making tasks in controlled settings. We thus explored the validity of the ingroup favoritism argument through a naturalistic helping task that entailed picking up "lost letters" and posting them back to the addressee. The field experiment was conducted in rural Australia, and the ingroup-outgroup distinction was established by varying the location of the receiver of the letter. We did not find any evidence of an ingroup bias in this spontaneous helping task. The only variable that significantly affected the likelihood of a letter being returned was socioeconomic prosperity of towns, a finding that corroborates our previous research in an urban environment. The lack of intergroup discrimination can be explained with the material security hypothesis, according to which the existence of institutions (public services, global markets, social safety nets) that ensure material security and safe interaction with strangers lessens the need for investments in local community members to meet people's basic needs.