It wouldn't surprise me if that were the case, to some extent. Mainly, I think it can be explained by the horrible Yahoo Search Marketing user interface. It's not immediately obvious that you have to set the bids for search vs. content separately, so I suspect a lot of people had the same bids for both, for a long time.
Even when you do realize it, there's another catch. If you set the bids on search from $1.00 down to $0.50, and then click over to the content page, it already shows the corresponding category as $0.50, which isn't true. It's still at $1.00. You have to update the category with the bid it already shows for it to actually have that bid.
So, I suspect that as more people figure out the awful interface, YPN bids are going to come down.