The answer is because not a single one of them (or their close constituents) have been educated enough on the FairTax. We need -YOU- to continually educate -YOUR- Congressmen and Senators about the FairTax.
Start with POPVOX. Visit each of the 3 links below and send your Congressmen and Senators an educational piece of material about the FairTax. Remember, Keep It Short & Sweet.