People heard her say that and were outraged. What's funny is that when you think about it, it actually does make sense although it's pejorative.
Rich people don't pay taxes. They invest their money, which is incentivized by the government in the form of lower/different taxation. Similarly they use experienced lawyers who understand the tax code to structure their wealth in ways that allow them to pay lower taxes. And the term little people, while pejorative, really represents the power differential between people like her husband and the "Average Joe". Trump is not little people, but he's somehow managed to express things in ways that "little" people (using Leona's terminology, not my own) like.
Much of politics is about not directly saying the truth, whether it be ugly, undesired, or complicated. Instead it's about understanding what drives voters (higher out of pocket prices uncoupled from concomitant wage increases) and how to say the thing they want to hear, while also enacting policies that achieve your political goals.