While I think that's generally true, particularly the resurgence of zombie fiction in pop culture that happened about 15 years ago, I can think of a number of notable exceptions like the Return of the Night of the Living Dead series which starts off hinging on the negligence of dipshit small business tyrants and directly compares the resulting zombie outbreak to older generations cannibalizing the young, then progresses into the general take of "actually military bioweapon research is bad" in stories where the zombies are basically elite individual monsters (I don't remember what the fifth movie was about apart from it being really stupid, like the Piranha 3D of zombie movies).

There was also some schlocky zombie movie called something like Rezort that I drunkenly watched a few years ago in which the zombies were explicitly the victims, being refugees held in private concentration camps that the villains were harvesting to turn into commodified zombies that they then sold to rich sociopaths who wanted to hunt them for sport.