"Night soil" is used by several cultures, but you have to be acclimated to it or it can make you really sick. IIRC, the Koreans are a notable group that used human waste as fertilizer--eating the local produce was a good way for GIs to get sick during the Korean War. Andy Weir actually covers this in The Martian when the main character is figuring out how to grow potatoes in sterile soil...Poor folks have poor ways and sometimes ignorant ways. (ignorant ways means unknowing, not stupid or dumb.)
I wonder how many po' folks on OSA has shoveled human waste for a garden? I'm sure I'm not the only one. Admit that you did, no one will know who you are anyway.