Hi,
Is there any reason the “plane” built in mesh has 200 tris? Is there one with just two tris somewhere? Do I really have to get my artist to make me a model with two tris just to map a simple texture onto it?
Sam
Search button above on the left, highly recommended! Seen a few posts here about it, Unity Answers has info as well. Shorts answers are: yes, not in Unity, and yes. Longer answer for the last one would be “no, it’s not hard to model it or script it yourself”.
I actually did search - I couldn’t find much 
My search-fu failed. Thanks though.
Pay attention to one thing: mesh colliders can have a maximum of 500 triangles if I remember correctly… so if you’re trying to create a plane because you want to model it in some way, you can only make it 500 triangles ‘big’ if you apply a mesh collider to it (and must set its collision detection to CONVEX, by the way)
Mesh Colliders can have as many triangles as you want. Convex Mesh Colliders, on the other hand, indeed have a limit (256 faces or something like that). But if you’ve got a plane, then it’s convex collider will only have just a couple of faces anyway (no matter what’s the tessellation level of the plane).