As a military retiree I sometimes need to shop or visit a military installation; when I know I'm going there I go unarmed. Fortunately I live near enough to the base that I can return home and arm up before beginning the rest of my errands. I'm going to be carrying anywhere and everywhere else; we don't have many restricted areas here in WA. If I need to drop something at the PO I'll wait in the car while my wife runs it in. If we're going out to eat I just need to stay out of the "bar area" of the restaurant (even though the hostesses seem to default to trying to seat us there).

All that to say, there is no reason that I would ever need to leave a handgun in the car. I have even carried openly into the police station to renew my CPL. When I worked in a federal building in a downtown area I used a lock-box with a cable. I didn't like its level of security but it was better than nothing and would have made theft of my handgun a lot more time consuming. I'm glad to be out of that situation now.