>The problem with that approach is that often they include ingredients in very small quantities that most people won't have, and buying the ingredient yourself requires getting a container with 1000x the amount you need. Even if it's cheap, people balk at that.

This is more of a problem with how fucked American supermarkets are and how much food wasted is generated not just by too much being packaged. I go out of my way to shop at Asian supermarkets because at least I can buy alot of produce individually and not massive bags of shit that'll spoil before I can eat it like American supermarkets push.