Another effect related to 2 is that many people probably think they can't find vegetarian dishes that taste as good as their preferred meat dishes. (I mean, I also think this. I don't currently know of any good substitutes for my preferred meat dishes.)

One more thing I'd like to add is that only after turning vegetarian I was first able to understand how severely I had been biased toward neglecting suffering in other species.

As long as we're talking in terms of biases, this could itself be regarded as a bias, namely a consistency effect.