Two questions: 1. Why does it need to be a constitutional ban? Why not just pass a law against it? 2. Why not make tax-return program publishers responsible f

Two questions: 1. Why does it need to be a constitutional ban? Why not just pass a law against it? 2. Why not make tax-return program publishers responsible for any errors their programs make, and make honest tax payers exempt from liability due to relying on what they believed was a correctly functioning tool?