Without looking for it in the .xml I'd say that the default scout blueprint has something like:
<RequiredComponent>LifeSupport<RequiredComponent>
<RequiredComponent>LifeSupport<RequiredComponent>
<AllRequiredMustFit>True<AllRequiredMustFit>
While the blueprint for the scout you build in your shipyard reads (here I looked):
<ShipBlueprint>
<InternalName>ScoutBlueprint</InternalName>
<ShipHullType>Tiny</ShipHullType>
<Role>Support</Role>
<ShipGroup>Scout</ShipGroup>
<RequiredComponentType>Sensor</RequiredComponentType>
<RequiredComponentType>LifeSupport</RequiredComponentType>
<ComponentType>InterstellarDrive</ComponentType>
<ComponentType>LifeSupport</ComponentType>
<ComponentType>LifeSupport</ComponentType>
<ComponentType>LifeSupport</ComponentType>
<ComponentType>InterstellarDrive</ComponentType>
<FillerComponentType>LifeSupport</FillerComponentType>
</ShipBlueprint>
Limiting its loadout to available capacity.