diff --git a/codegen-core/src/main/kotlin/software/amazon/smithy/rust/codegen/core/smithy/generators/StructureGenerator.kt b/codegen-core/src/main/kotlin/software/amazon/smithy/rust/codegen/core/smithy/generators/StructureGenerator.kt
index 80d89e341ff..993914b97c8 100644
--- a/codegen-core/src/main/kotlin/software/amazon/smithy/rust/codegen/core/smithy/generators/StructureGenerator.kt
+++ b/codegen-core/src/main/kotlin/software/amazon/smithy/rust/codegen/core/smithy/generators/StructureGenerator.kt
@@ -16,12 +16,14 @@ import software.amazon.smithy.rust.codegen.core.rustlang.RustWriter
 import software.amazon.smithy.rust.codegen.core.rustlang.asDeref
 import software.amazon.smithy.rust.codegen.core.rustlang.asRef
 import software.amazon.smithy.rust.codegen.core.rustlang.deprecatedShape
+import software.amazon.smithy.rust.codegen.core.rustlang.docs
 import software.amazon.smithy.rust.codegen.core.rustlang.documentShape
 import software.amazon.smithy.rust.codegen.core.rustlang.isCopy
 import software.amazon.smithy.rust.codegen.core.rustlang.isDeref
 import software.amazon.smithy.rust.codegen.core.rustlang.render
 import software.amazon.smithy.rust.codegen.core.rustlang.rust
 import software.amazon.smithy.rust.codegen.core.rustlang.rustBlock
+import software.amazon.smithy.rust.codegen.core.rustlang.stripOuter
 import software.amazon.smithy.rust.codegen.core.smithy.RuntimeType
 import software.amazon.smithy.rust.codegen.core.smithy.RustSymbolProvider
 import software.amazon.smithy.rust.codegen.core.smithy.customize.NamedCustomization
@@ -131,15 +133,26 @@ open class StructureGenerator(
         writer.rustBlock("impl $name") {
             // Render field accessor methods
             forEachMember(accessorMembers) { member, memberName, memberSymbol ->
-                writer.renderMemberDoc(member, memberSymbol)
-                writer.deprecatedShape(member)
                 val memberType = memberSymbol.rustType()
+                var unwrapOrDefault = false
                 val returnType = when {
+                    // Automatically flatten vecs
+                    memberType is RustType.Option && memberType.stripOuter<RustType.Option>() is RustType.Vec -> {
+                        unwrapOrDefault = true
+                        memberType.stripOuter<RustType.Option>().asDeref().asRef()
+                    }
                     memberType.isCopy() -> memberType
                     memberType is RustType.Option && memberType.member.isDeref() -> memberType.asDeref()
                     memberType.isDeref() -> memberType.asDeref().asRef()
                     else -> memberType.asRef()
                 }
+                writer.renderMemberDoc(member, memberSymbol)
+                if (unwrapOrDefault) {
+                    // Add a newline
+                    writer.docs("")
+                    writer.docs("If no value was sent for this field, a default will be set. If you want to determine if no value was sent, use `.$memberName.is_none()`.")
+                }
+                writer.deprecatedShape(member)
                 writer.rustBlock("pub fn $memberName(&self) -> ${returnType.render()}") {
                     when {
                         memberType.isCopy() -> rust("self.$memberName")
@@ -148,6 +161,9 @@ open class StructureGenerator(
                         memberType.isDeref() -> rust("use std::ops::Deref; self.$memberName.deref()")
                         else -> rust("&self.$memberName")
                     }
+                    if (unwrapOrDefault) {
+                        rust(".unwrap_or_default()")
+                    }
                 }
             }
         }
diff --git a/design/src/rfcs/rfc0035_collection_defaults.md b/design/src/rfcs/rfc0035_collection_defaults.md
index 218782f7894..2237c02b2b2 100644
--- a/design/src/rfcs/rfc0035_collection_defaults.md
+++ b/design/src/rfcs/rfc0035_collection_defaults.md
@@ -3,7 +3,7 @@ RFC: Collection Defaults
 =============
 
 <!-- RFCs start with the "RFC" status and are then either "Implemented" or "Rejected".  -->
-> Status: Accepted
+> Status: Implemented
 >
 > Applies to: client
 
@@ -78,5 +78,5 @@ No, many existing APIs don't have the default trait.
 Changes checklist
 -----------------
 Estimated total work: 2 days
-- [ ] Update accessor method generation to auto flatten lists
-- [ ] Update docs for accessors to guide users to `.field.is_some()` if they MUST determine if the field was set.
+- [x] Update accessor method generation to auto flatten lists
+- [x] Update docs for accessors to guide users to `.field.is_some()` if they MUST determine if the field was set.