You should watch a few documentaries about industrial scale food factories, especially meat: https://www.dailymotion.com/video/x10tzbi
What ends up in a lot of supermarket patties is the leftover of all the other "higher quality" meat parts, you get stuff like https://en.wikipedia.org/wiki/Aponeurosis &c. which don't exist in regular minced meat. We even have a term for these in France, "minerai de viande", literally "meat ore", back in the days it mostly went to the trash or for animal food. Some products are so processed that they can't be legally named "meat" but "meat preparations"