Children in the Car

So I am craving a diaglogue with my mom friends. But they are on vacation or far away and I am insane and planned way too many activities for spring break to gather some moms for conversation. Maybe you can tell me your thoughts here. Can I leave my two girls in the car while I run into a store for a quick errand? Thirty years ago the answer was yes. I remember being left in the car while mom picked up a few groceries. How old was I, mom? I knew enough then that I would get a little worried if an unkempt man walked too close, because in my mind all kidnappers were male, unkempt, and smelly. My kids are trained, as much as is possible. They know about stranger danger, they know how to get in and out the car, and of course I consider the temperature and don't leave the keys in the car. The safety basics are covered. But in this crazy world, in this current time period, can anyone leave kids in the car alone? And if yes, how old do they have to be? Can I run in for 1 minute? or five? What about ten? Can I only run in if I can see the kids from the window of the store, like at UPS or if I park strategically at the post office? Is this a practice from the olden days that can't continue? A practice that can only continue in small towns? What do you think? Do you shake your head shamefully if you see kids alone in the car?