When using Unity's UI shaders that have an additional detail texture set in the second UV channel, the result very different when comparing with the shader code and has to be tweaked to obtain the correct result. Also, the use of the PositionAsUV1 component (which is required for the detail texture to show up) isn't mentioned in the documentation, which can be very confusing.

To reproduce:

1. Make a new Unity Project.
2. In the Hierarchy, Click Create>UI>Image
3. Assign a sprite from your Texture to the Image's Source Image
4. Create a Material.
5. Assign the Shader UI/Unlit/Detail (any default UI shader would work as the meshes are produced the same)
6. Add a texture to your project to use as the Detail Texture in your Material.
7. Add the texture to the Material.
8. The resulting material is incorrect as the detail texture doesn't show up.

In the attached project you can find a comparison between a UI Image with the detail shader and a Quad with a standard shader that uses the same detail map (which is how the UI image should look).

Reproducible: 5.6.0b3, 5.5.0p4, 5.4.3p4, 5.1.3p3