Have you ever taken your keys out when you're at/leaving a store?

No. Why would you? The casualness with which the question is put makes me curious, but my home keys are generally something I use in the door at home, not at the store.

Those of us who use cars often keep our car keys and house keys on the same keyring. While walking out the door of the store you pull your keys out.

The thought hand't actually occurred to me to keep my car keys on my key ring. They're gigantic these days. But I guess a lot of people do.