Texture coordinates in shader are negative

I was expecting that texture coordinates in a surface shader would be in the range [0, 1]. However I get negative values. Why is that? The following shader I would expect an output of all green, however it outputs some red on edges. I am new to shaders in Unity, so please let me know if I can provide any more information.

 Shader "Custom/MyShader" {
 Properties {
     <...>
     _Image("Image", 2D) = "white" {}
     <...>
 }
 SubShader {
     Tags { "RenderType"="Opaque" }
     LOD 200

     CGPROGRAM
     #pragma surface surf Standard fullforwardshadows 
     #pragma target 3.0

     sampler2D _Image;

     struct Input {
         float2 uv_Image;
     };

     half _Glossiness;
     half _Metallic;
     fixed4 _Color;

     // Add instancing support for this shader. You need to check 'Enable Instancing' on materials that use the shader.
     // See https://docs.unity3d.com/Manual/GPUInstancing.html for more information about instancing.
     // #pragma instancing_options assumeuniformscaling
     UNITY_INSTANCING_BUFFER_START(Props)
         // put more per-instance properties here
     UNITY_INSTANCING_BUFFER_END(Props)

     void surf (Input IN, inout SurfaceOutputStandard o) {
         
         fixed4 c = float4(0, 1, 0, 1);

         if (IN.uv_Image.x < 0 || IN.uv_Image.y < 0) {
             c = float4(1, 0, 0, 1);
         }
         o.Albedo = c.rgb;
         o.Metallic = _Metallic;
         o.Smoothness = _Glossiness;
         o.Alpha = c.a;
     }
     ENDCG
 }
 FallBack "Diffuse"

}