I also use Python or bc as a desktop, but that really isn't the point.

People sometimes criticize the Windows calculator for perceived errors in the results even though it is a superficially simple program. What they fail to account for are the edge cases, those quirks of computation that manifest themselves for various reasons (e.g. the precision of floating point, simplifications that appear simple to a person yet are non-trivial to implement in a program). A shipping product is not the same thing as a simple calculator tutorial a novice programmer may follow.