The problem with your rationale is that you have no idea whether there is an error or not when you get the figure at the end. If I add income I should expect the refund to go down...deduction it goes up...if it does the opposite of what I think I think I have somehow done something wrong and oftern have. I think the reasoning for this is that it makes people change their deductions to get to zero. Well, that is freedom for you!
