I only use a cheap, $5 combo cable lock. Why? because I never leave my bike fully unattended. Why carry a bulky, heavy lock at a lunch stop? If I see someone scoping out my bike, I am on them like a fly on doggie manure.
So, for people like me that want a lightweight, quick anti-snatch solution, we get simple cable locks. If I were to go into a resturaunt or grocery store, I don't take my bike with me unless I can keep it in relatively good view or at my side. I've even considered getting a Brompton as they fold into shopping carts.