I've found that a surprising number of people (outside of fields like math, engineering, programming) are used to the idea of entering an operation and having it applied to the current value. E.G: pressing the [√] button immediately square roots the current number, pressing [X][2] doubles the current number, etc.
It's a different paradigm to using the buttons to enter a full expression then pressing [=] to evaluate it, but I don't think it's accurate to call it "the wrong thing" - just that the button presses aren't transcribing to the equation you expect (the equation actually displayed by Windows 10 calculator is now accurate).