Why pixel artifacts on aligned cubes?

There seem to be lots of posts on this but without satisfactory answers. I know quite a bit about 3D rendering (primarily OpenGL) and something does seem to be going on. See this screenshot marked up with the artifacts:

The project is [28053-testunity.zip|28053].

Now this is a project freshly created in Unity 4.5 on OS X (Mavericks) running on MacBook Air (2011 version). Should be an easily supported platform.

The first row of cubes (closest to screen with z=0) are just 8 unit cubes, positioned at 1, 2, 3 etc. with no parents. You can verify the transforms in the (forced text) scene file, they look like:

m_LocalRotation: {x: 0, y: 0, z: 0, w: 1}
m_LocalPosition: {x: 0, y: 0, z: 0}
m_LocalScale: {x: 1, y: 1, z: 1}

m_LocalRotation: {x: 0, y: 0, z: 0, w: 1}
m_LocalPosition: {x: 1, y: 0, z: 0}
m_LocalScale: {x: 1, y: 1, z: 1}

Next row (z=1) is same, but moved 0.5 to the right.

m_LocalRotation: {x: 0, y: 0, z: 0, w: 1}
m_LocalPosition: {x: 1.5, y: 0, z: 1}
m_LocalScale: {x: 1, y: 1, z: 1}
etc.

Next row also offset by 0.5 in the x direction, and is at z=2 in an empty parent at z=2 (otherwise all at origin).

The last row is a copy of the third parent, moved to z=3, and the cubes are shrunk to 0.5 in the y direction and moved to y=0.25.

All these should be perfectly aligned (floating point can be “approximate” but not in the case of 1, 0.5, and 0.25) given their coordinates and parents. In OpenGL, vertices with the same floats are guaranteed to rasterize lines between them perfectly the same no matter which primitive they are from, to avoid precisely this problem. So it’s not a problem I’d expect in Unity, given the scene setup.

However, all rows exhibit pixel artifacts at the seams, in both the scene view, the game view (small), and the game view (full screen). Depending on the exact camera position/orientation, the pixel artifacts scintillate along the seams.

The material is a simple blue diffuse, with a single directional light. The camera is orthographic.

So what’s going on? I’d like an explanation beyond “vertices are fuzzy” or “try expanding your cubes” because something is definitely amiss. Thanks.

I HAVE FOUND A SOLUTION THOUGH FOR THIS AWFUL PROBLEM:
Fiddle around with the “Clipping Planes” of your main camera. I have changed my clipping plane (near) of my main camera from .01 to 1, and suddenly all grid artifacts are gone!