Automatic alignments in games and other media bother me.

We all know that people aren't inherently good or evil from when they're born but develop that way, so why make characters like that? I mean you could say it's the culture but even then culture has never been a predictor of morality (and on an aside, why are races in fantasy media seemingly one-culture exclusive? It's not like all white or black or hispanic or whatever people have the same backgrounds across the land, and that doesn't even account for all the various subcultures that probably aren't racially defined to begin with).

You're thinking from a modernist perspective where human cultures have extensively intermingled for thousands of years and we have very little competition with each other for resources.
If you look back even a couple hundred years ago our own world was similarly divided. Native americans were completely ensconced in their culture and to the invading christians that made them evil heathens.
In fantasy settings most races have not not had extensive contact with one another. They're all bound in their own cultural beliefs with the so called 'evil races' being defined by having traditions and beliefs in conflict with the so called good races. It's all perspective. Differing ideologies brook wars even today as Israel and Palestine show us weekly.