In the configs for vehicles and weapons (including attachments), the DLC property is often missing or occasionally falsely flagged as an DLC when vanilla / platform feature.
This issue makes it impossible to write a UI script that can show required DLC for items a player is about to purchase or choose.

The DLC property should return what DLC the player needs to use that object or a new config property could be added.

An alternative solution could be adding a script command to query what DLC is needed (Steam ID or CfgMod name) for a given classname or config entry.