Actually, when this happened to me, my debit card company told me to try to talk to the retailers first. And as I posted earlier in this thread, I was able to handle it with one of the retailers without having to do a chargeback. With iTunes, it doesn't sound like people have been lucky with that. In my case, the iTunes charges were for small amounts and were pending charges that eventually dropped off, so I didn't have to do a chargeback for them. But it's not crazy for people to try to get it worked out with iTunes (just not very effective).
I wonder if there are two issues here. Mine was definitely a stolen credit card number, with iTunes as one of the false charges, on a card I have never used myself with iTunes. The other fraudulent charges were for different online companies. It seems like if someone is stealing/buying stolen credit card numbers, testing them with small charges on iTunes might be something the thieves would do. Other people, though, seem to be seeing incorrect charges on the card they actually use for iTunes, raising the question of some kind of billing error on the part of iTunes. I think it's one thing if iTunes isn't that helpful when someone uses a stolen card number with them, but it's a lot more concerning to me if they are making errors and are then unwilling to help fix them.