It seems to me many of these tests are asking pie charts to do something they're really not meant for. Sure, you can create a synthetic problem and dataset wher

It seems to me many of these tests are asking pie charts to do something they're really not meant for. Sure, you can create a synthetic problem and dataset where you need to order four different categories, all comprising around quarter of the whole, and there a bar chart would excel. But that's not actually that common a use case: a lot of the time, I'd only be interested that they are all roughly a quarter of the whole, and not care beyond that (providing a ranking of small differences can actually be pretty misleading, depending on the problem you're trying to answer). I can just as easily say, I want to know roughly what proportion of the whole a category comprises. And with widely varying category sizes, the pie chart excels, while with a bar chart I'd have to sum the bar sizes in my head, and divide that total by the category in question. That's at least as taxing as having to differentiate between small differences in pie slice sizes. The answer isn't "always use pie charts" or "never use pie charts": it's to use what's best for a particular situation and context.