It depends. Mom & Pop store makes an error in my favour, I will make the effort to get things corrected. Big box store? I might if it's not too inconvenient for me. Someone, say, leaves a pile of money on a desk at work or their wallet in a bar? Doesn't matter how much cash, it's safe However, an untended box of cookies, bag of potato chips or plate of fries? Yeah, I'm taking one.