Someone (maybe on another thread, I am not sure) mentioned that sellers can no longer block buyers with low or no feedback scores. if so, that could explain a rise for some sellers in their number of unpaid items.

But for a rise in the number of suspected scams, where people claim they didn't receive an item, knowing full well that a seller cannot prove they arrived when sent unregistered, then you'd think that would be more likely to be people who have had at least a minimum of experience on ebay, to be familiar with the system and how to claim etc

It is strange if it has become worse in recent times, I'm not sure why that would be, maybe you have just had a run of bad luck.