Why does this code work without any "Pass{}" expressions? And is there a way to add shadow collections?

Hey guys! I don't know much about shaders, but I found this shader on the internet. I turned culling off for both of the passes. My character consists of some sprites that are flipped, and I wanted them all to be visible and to cast shadows on the same side. I only vaguely understand the code. Just enough to get it working for my purposes. So, my question is two-fold:

1. Why are there no Pass{} expressions? Aren't you supposed to surround each pass with one? Or is that optional?

2. How do I add shadow collections to the shader? I tried adding this section of code, but it didn't do anything:

   // Pass to render object as a shadow collector Pass { Name "ShadowCollector" Tags { "LightMode" = "ShadowCollector" }

            Cull Off//new 
               Lighting On //new
                Fog {Mode Off}
                ZWrite On ZTest LEqual
         
                CGPROGRAM
                #pragma vertex vert
                #pragma fragment frag
                #pragma fragmentoption ARB_precision_hint_fastest
                #pragma multi_compile_shadowcollector
         
                #define SHADOW_COLLECTOR_PASS
                #include "UnityCG.cginc"
         
                struct appdata {
                    float4 vertex : POSITION;
                };
         
                struct v2f {
                    V2F_SHADOW_COLLECTOR;
                };
         
                v2f vert (appdata v)
                {
                    v2f o;
                    TRANSFER_SHADOW_COLLECTOR(o)
                    return o;
                }
         
                fixed4 frag (v2f i) : COLOR
                {
                    SHADOW_COLLECTOR_FRAGMENT(i)
                }
                ENDCG
         
            }
   
    
   
   

Shader "Sprites/Bumped Diffuse both sides with Shadows 2" { Properties { [PerRendererData] _MainTex ("Base (RGB)", 2D) = "white" {} _BumpMap ("Normalmap", 2D) = "bump" {} _Color ("Tint", Color) = (1,1,1,1) [MaterialToggle] PixelSnap ("Pixel snap", Float) = 0 _Cutoff ("Alpha Cutoff", Range (0,1)) = 0.5

      }
  
      SubShader
      {
          Tags
          { 
              "Queue"="Transparent" 
              "IgnoreProjector"="True" 
              "RenderType"="TransparentCutOut" 
              "PreviewType"="Plane"
              "CanUseSpriteAtlas"="True"
              
          }
          LOD 300
  
          // Render back faces first
          Cull Off
          Lighting On
          ZWrite Off
          Fog { Mode Off }
          
          CGPROGRAM
          #pragma surface surf Lambert alpha vertex:vert addshadow alphatest:_Cutoff 
          #pragma multi_compile DUMMY PIXELSNAP_ON 
  
          sampler2D _MainTex;
          sampler2D _BumpMap;
          fixed4 _Color;
          float _ScaleX;
  
          struct Input
          {
              float2 uv_MainTex;
              float2 uv_BumpMap;
              fixed4 color : COLOR;
          };
          
          void vert (inout appdata_full v, out Input o)
          {
              #if defined(PIXELSNAP_ON) && !defined(SHADER_API_FLASH)
              v.vertex = UnityPixelSnap (v.vertex);
              #endif
              float3 normal = v.normal;
              
              v.normal = float3(0,0,-1);
              v.tangent =  float4(1, 0, 0, 1);
              
              UNITY_INITIALIZE_OUTPUT(Input, o);
              o.color += _Color;
          }
  
          void surf (Input IN, inout SurfaceOutput o)
          {
              fixed4 c = tex2D(_MainTex, IN.uv_MainTex) * IN.color;
              o.Albedo = c.rgb;
              o.Alpha = c.a;
              o.Normal = UnpackNormal(tex2D(_BumpMap, IN.uv_BumpMap));
          }
          ENDCG
          
          // Now render front faces first
          Cull Off
          Lighting On
          ZWrite Off
          Fog { Mode Off }
          
          CGPROGRAM
          #pragma surface surf Lambert alpha vertex:vert addshadow alphatest:_Cutoff 
          #pragma multi_compile DUMMY PIXELSNAP_ON 
  
          sampler2D _MainTex;
          sampler2D _BumpMap;
          fixed4 _Color;
          float _ScaleX;
  
          struct Input
          {
              float2 uv_MainTex;
              float2 uv_BumpMap;
              fixed4 color: COLOR;
          };
          
          void vert (inout appdata_full v, out Input o)
          {
              #if defined(PIXELSNAP_ON) && !defined(SHADER_API_FLASH)
              v.vertex = UnityPixelSnap (v.vertex);
              #endif
              float3 normal = v.normal;
              
              v.normal = float3(0,0,1);
              v.tangent =  float4(1, 0, 0, 1);
              
              UNITY_INITIALIZE_OUTPUT(Input, o);
              o.color += _Color;
          }
  
          void surf (Input IN, inout SurfaceOutput o)
          {
              fixed4 c = tex2D(_MainTex, IN.uv_MainTex) * IN.color;
              o.Albedo = c.rgb;
              o.Alpha = c.a;
              o.Normal = UnpackNormal(tex2D(_BumpMap, IN.uv_BumpMap));
              o.Normal.z *= -1;
          }
          ENDCG
          
 
    
         // Pass to render object as a shadow collector
         Pass {
             Name "ShadowCollector"
             Tags { "LightMode" = "ShadowCollector" }
            
            Cull Off//new 
            Lighting On //new
             Fog {Mode Off}
             ZWrite On ZTest LEqual
      
             CGPROGRAM
             #pragma vertex vert
             #pragma fragment frag
             #pragma fragmentoption ARB_precision_hint_fastest
             #pragma multi_compile_shadowcollector
      
             #define SHADOW_COLLECTOR_PASS
             #include "UnityCG.cginc"
      
             struct appdata {
                 float4 vertex : POSITION;
             };
      
             struct v2f {
                 V2F_SHADOW_COLLECTOR;
             };
      
             v2f vert (appdata v)
             {
                 v2f o;
                 TRANSFER_SHADOW_COLLECTOR(o)
                 return o;
             }
      
             fixed4 frag (v2f i) : COLOR
             {
                 SHADOW_COLLECTOR_FRAGMENT(i)
             }
             ENDCG
      
         }
         
         
          
      }
  
  Fallback "Transparent/Cutout/Diffuse"
  }