Despite scat being a common-ish fetish in the community, almost no artists draw realistic animal feces despite the fact the entire fandom revolves around animals.

Likely because the vast majority of those who might care enough to do the required research are simply not interested in doing so, and that assumes it even occurs to them that there might be a difference.

You say that like the vastly more common (within this fandom) fetish for animal genitals isn't also almost entirely inaccurate to how they look or work in real life.

I tend to draw it fairly similar now while still focusing on the act of pooping. Trying to get better about it but as was said, it takes a lot of skill and research to draw it. For example, most people dont draw dicks correctly and tend to just do human dicks or just the normal way people draw them now but the issue remains of people not wanting to do the work to make porn.