Comment by hellojesus

My assumption is that the weight of including vegans socially is too much to bear for some. On the extreme end, you can't use store pasta because it was made in a facility that processes eggs and dairy. But even on the lighter end, social eating modification is pretty extreme: don't use butter when cooking, or eggs, or honey, etc. It's a lot easier to accommodate vegetarians than vegans.

Though I do have a vegan friend that always brings her own food to gatherings, and it does make things far easier.