The prerequisite is in the itemtype, not the tech. CoreItems.xml
    <GameItemType InternalName="QuestMap">
        <DisplayName>Quest Map</DisplayName>
        <Description>These maps can be used as clues to unique opportunities in the world.</Description>
        <ShopValue>100</ShopValue>
        <GameModifier>
            <ModType>Map</ModType>
            <Attribute>CreateQuestNearTile</Attribute>
            <BoolVal1>1</BoolVal1>
            <Value>-1</Value>
            <Radius>-1</Radius>
            <Provides>Spawns a new quest</Provides>
        </GameModifier>
        <IsAvailableForSovereignCustomization>0</IsAvailableForSovereignCustomization>
        <Likelihood>200</Likelihood>
        <RarityDisplay>Uncommon</RarityDisplay>
        <HeroOnly>1</HeroOnly>
        <IsAvailableForUnitDesign>0</IsAvailableForUnitDesign>
        <IsUsable>1</IsUsable>
        <Prereq>
            <Type>AbilityBonusOption</Type>
            <Attribute>Wanderlust</Attribute>
            <Target>Player</Target>
        </Prereq>
        <Prereq>
            <Type>Tech</Type>
            <Attribute>Breons_Letters</Attribute>
        </Prereq>
        <ArtDef>QuestMap_ArtDef</ArtDef>
        <GameItemTypeArtDef InternalName="QuestMap_ArtDef">
            <GameItemTypeModelPack InternalName="QuestMap_Default">
                <IconFile>Parchment1.png</IconFile>
                <TintR>0</TintR>
                <TintG>0</TintG>
                <TintB>0</TintB>
                <GameItemTypeModel>
                </GameItemTypeModel>
            </GameItemTypeModelPack>
        </GameItemTypeArtDef>
    </GameItemType>
This is mostly how it works (children attach to their parents rather than parents attaching to their children), with some small exceptions such as unlockable skills from wearing items.