Developers can't know everything there is to know in the world. Developers aren't suppose to know specific stuff like this. Some parts of modern society are easy to digitalize, other (often historical) parts aren't. I think it's up to entrepeneurs to find ways to solve these problems, and create a better world by doing that. Don't blame/shame developers for stuff like this. It's not even remotely fair.

When you're training developers remember that you're not training demigods.