Missing? Repercussions...
If the plan is to hijack vehicles/drones that are unattainable at CharGen, the normal reason for this is that they are high-end devices.
As such, they will have high-end security (not just what's listed under the off-the-shelf models) and more than likely be owned by people on the Knight Errant VIP list, guaranteeing a very fast response time.
Should it be possible? Sure
Should it be an easy, cookie-cutter process? Oh hell no

Drones and Vehicles aren't my forte, but as examples:
- Escorts. These things may have friends
- Passive RFID. These things are damned hard to find and erase, especially on larger vehicles
- Speed: The high-end stuff is normally pretty fast, and could be dodging wi-fi (or getting interference) pretty easily.
- Upgraded defenses: Firewalls, Riggers, even Magical security. All these are great options to keep other people's sticky fingers off your shiny toys
