Let’s get another easy one out of the way as long as we haven’t even named this feature yet. In Australia, the price on a menu or price list is the actual price that something costs. In the United States, without even getting into tipping yet, the sales tax is added onto the listed price.
In the US, you end up reflexively adding X%–the amount varies from state-to-state–and still you stand at the register and think, “Gee, with tax that added up to more than I thought.” It’s so much more convenient to just have the price you see be the price you pay that it even takes some getting used to when buying more expensive items. That is, I realized it’s a regular part of my routine when buying something to think, “OK, but what does it cost really?” that it takes some doing to recognize that what you see is what it is.
Jeremy’s winner: Oz (don’t worry, this won’t end up being all about the wonders of Oz)