MLE, you're one of my favorites here and I make a point of reading everything you write. So I don't mean any disrespect by saying that there appears to be a problem with an esoteric definition of terms.
I gave the classic example of the salesman who steps on skateboard left out on the front porch and you pointed out that this situation was different because both the parents and child were already familiar with the situation and should have "expected" it.
But it is easy to make the example a closer parallel. Instead of a salesman on a cold-call, let's assume it's the mailman and he's delivered to this address for a solid 5 years. There have always been skateboards left out on the front porch and he's always stepped around them before.
Does that change his expectation of an unobstructed walkway? No. --We're not talking about his perceptions.
It does not matter if he's seen the skateboards a thousand times or even a million times before. When we talk about the mailman's "expectation" of an unobstructed walkway, we're talking about the fact that the law requires that walkways be unobstructed.
When a pedestrian negotiates a hazard without injury, that's great, but accidents by their very nature are things that happen that one time you forget or that one time you trip or that one time you're distracted. What then? Negligence and liability are decided by the material details, not intangibles like the victim's alleged perceptions and state of mind. The questions are simple: Was there an unsafe condition? Who was responsible for the unsafe condition?
Stating that the victim should have known that you were negligent based on a past history of creating and tolerating a hazardous condition is no defense at all. Think what a disaster it would be if that became a viable legal defense for an entity like a public utility:
"The homeowner should have known we would install a faulty gas meter. The last two we installed were faulty and many other homes in the neighborhood had the same problem. It's not our fault his house burned down. It's his fault for turning on the furnace."
This thread really seems to be touching a nerve and I'm sorry about that. But it's not going to fade away when the child and the child's parents are being disparaged as clumsy and irresponsible.