My last 10 years active duty was in the "Peoples Draconian State of MD" and weapons had to be "secured" in a separate compartment from you and the ammo. I was also a member of the local, very busy rescue squad and my vehicle would sometime end up in “interesting” neighborhoods. Also, if I were in an accident, as Unobtanium sez, the interested party that would scavenge your vehicle would at least be frustrated for a while.
Even now that I’m in a free state, I still carry over those old habits for those weapons that aren’t readily available anyway.