Really ? You really wonder that ?
mixture, was that really necessary? Indigo is asking for information, and you effectively call them an idiot - why did you do that? Would you like people to treat you the same way when you ask a question?
The other replies have been far more sensible - despite flying the Airbus for 8 years, I personally hadn't thought of the parallel processing angle - the computers are distributed around the flight controls, which would indeed give quick response, rather than one doing everything.
Many designers and engineers at Airbus will have had many "strokey beard" sessions to decide how many items and back-up items would be needed in every part of the aircraft. They would have done a risk analysis and not included more than was considered necessary. There are 5 FBW computers and 2 FAC's - (flight augmentation computers), all of which translate the side stick or autopilot commands into flight control responses. This gives a high level of redundancy. I think I'm right in saying (please correct me) that each computer is of a different design and has different software written by different software suppliers, so not only do the computers back each other up, they do so with different methods and philosophies, which is an additional safeguard.
I was also told, but don't know if it is actually true; of the FBW fighter jet that was the new whizz-bang thing, but one day it crossed the equator and flipped inverted - someone had missed a minus sign out of the program and it hadn't been spotted.