Licences and Qualifications
Many skills give you a default to related categories eg Driving (Wheeled) 1 would also give you a default in, say Driving (Tracked) of 0.
However you are only considered licenced if you have a skill level of 1 or more. Thus with Pilot 0, even though your DEX might give you a bonus of +2, no one is going to hire you as a Pilot, or rent you a Ship, because you’re not qualified to fly it.
In some circumstances Lvl 0 might be considered a Provisional or Military licence, or similar