Leaving a gun in a locked vehicle is not "wrong."
What's wrong is that people smash windows and steal stuff from cars.
This gets touchy and has many shades of grey between black and white. We have to straddle a fine line between "blaming the victim" and figuring out how to "refuse to be" one.
It would be wrong for someone to steal your gun if you left it lying on a lawn chair in the middle of your front yard. But that would be a stupid place to leave one. People steal stuff left out in the open all the time. We all know this.
It would be wrong for someone to steal your gun if you left it in your purse or shoulderbag unattended on a bench in a public park. But that would be a stupid place to leave one. People steal unattended bags with near perfect regularity. We all know this.
It would be wrong for someone to steal your gun if you left it in your unlocked car, or on the front seat or dashboard of your car, but those would be stupid places to leave them. Cars are absolute theft
magnets. We all know this.
Now it would be wrong for someone to steal your gun out of your belt holster, or out of your gun safe at home. But those AREN'T stupid places to leave one because they're the best you can reasonably do to protect them.
Leaving it in a car in a parking lot at the post office for a 3 minute drop off?
Leaving it in a car in a parking garage while you shop for 4 hours?
Leaving it in a car parked at your farmhouse in the middle of 500 acres?
Leaving it in a car parked on the street in your suburban or urban neighborhood?
Parked under a security camera?
Parked outside your apartment?
Put it in one of those little lock boxes?
Hide it under some rags and junk mail?
Shades of grey. Some of us just WON'T. Some will roll those dice every day.