The thing is, everybodys bodies are not old fat heavy metal dumps with nonfunctioning livers. I can eat meat and not have to worry about my liver.
But what you seem to be ignoring is that vegetables and fruits are not good sources of zinc, at all. The 2 vegetables with significant amounts of zinc are spinach and collard greeners, they both harbor oxalic acid which hinders the absorbtion of the zinc.
When I eat meat, I get adequate amounts of zinc but I would like to get some more zinc into my body without having to eat 4 beef steaks everyday.