It’s one of those opportunity crimes where the easiest victim generally picked. It usually comes down to just two things:
How many people see your porch
How easy is it to walk up and walk away?
You’d be surprised how much of a deterrent a mild inconvenience is. You’ll get significantly fewer packages that walk off if you live on a big hill, or have a bunch of steps, where it’s mildly inconvenient for someone to walk up.