Because an ethical Venn diagram would have the interest groups concerned about both as a heavy cross over.
I imagine vegans would be a very small subset. I can’t imagine there are many pro-hunting vegans. But there are many many anti-hunting omnivores and vegetarians.
Nick Knowles summed it up perfectly in an interview: “I’m a vegan, but I’m not a tawt about it”. One tries to be true to ones ethics, but accepts that there will always be the occasional compromise. For him it was going round to a friend who’d cooked especially and forgotten he didn’t eat meat.
It would be a very strict vegan who turned down anti-cancer monoclonal antibodies. (They are all made in animal cells in a bioreactor), and of course will have historically been tested on animals. But they are, in essence, an animal cell-based product.