"I know I sound like I'm victim blaming, but if you put your stuff in a risky place, you bear some responsibility if it is damaged."
The same could be said of wearing an expensive suit to dinner because the server might drop your marinara in your lap. The point is that part of the server's job is to get the meal on the table without spilling, and the fact that there's an expensive piece of electronic hardware on the table doesn't change that responsibility.
"I've seen occasions where the item on the table is what has caused the spill that damages it. Sever is going to put plate down, spots phone/camera sitting on table in the road, tries last second move to put plate somewhere else so they don't put it on the item and whoops, there is a spill. If said item wasn't in the road, there wouldn't have been a spill. In that case it's all one whoever left the item there."
I disagree. It's common sense for a server to check where the plate is going before it becomes a "last second move" unless the customer tossed the phone under the plate on the way down, since a fork or bread plate could cause the same issue. As I said above, part of the server's job is to get the meal on the table without spilling it, and although accidents do happen that doesn't excuse the server from being responsible for the spill.
"I think that apologizing was the right thing for you to do, but you personally don't owe the customer anything more."
I agree that the server shouldn't be held personally liable for the damage done, because as an employee working in a professional capacity, it's the restaurant's job to cover that sort of thing.
"I don't think that the restaurant does either..."
This is where I disagree. The restaurant's employee did something that reasonably constitutes failure to do their job properly and as a result, damage occurred. Therefore, I do see the restaurant as responsible for the damage. If they want to avoid liability for such things, then at the very least a blanket disclaimer (or having the servers ask people to move expensive things to a safe location during the meal) is necessary. An expectation to be able to buy a meal without having it spilled on your stuff is reasonable. Accidents happen, but as CocoCamm wrote, if someone hits my car by accident, it's still on them to make it right.