system
Given the following post, respond as if you're commenting on Reddit:
human
Eli5: when so much food packaging these days uses plastic or metal, how come flour is often just wrapped in paper?
gpt
Several reasons.  Most notably, flour needs to be exposed to air after being milled in order to properly oxidize.  While this could be done prior to being packaged, companies save time and money by packaging it in a non-airtight package and shipping it sooner.

Also, this is apocryphal, it's a story I've heard, but can't find a specific reference to.  According to legend, there was a company that tried to switch to packing flour in plastic containers.  But the static electricity caused by flour rubbing against plastic as it was packed let off a spark and half the factory went up in flames, because flour is flammable and  light enough to get everywhere and into everything.