"Now a business will have 50 tax collection agency to deal with. The states will take over the IRS's job. 50 little IRSes, each with their own rules, regulation, procedures, etc... and business will have to file once a month to each of the states they do business in instead of once a year (or quarter) to one agency. So much for simplicity."
You are confusing state sales taxes, which are undoubtedly a mess, with the federal sales tax, which is what HR25 will bring about. Filing once a month with the states you do business in, for example, is a requirement of state sales taxes, not a federal tax.
Even on this front, however, there is good news. The FairTax will encourage states to "harmonize" their state sales taxes to the new federal NRST. There is already a movement afoot to standardize state and local sales taxes; the FairTax can realistically be expected to accelerate that trend. Most of the complexity in state sales taxes comes from differing rates and differing exemptions in different jurisdictions. Since the NRST is a single rate with no exemptions, at the very worst, we will be no worse off than we are today with respect to the complexity of collecting sales taxes, and a huge amount better off than we are with respect to income taxes.
Also, no matter how you slice and dice it, converting from the 60,000 page monstrosity that we have now to a system that is less than 1,000 pps. will result in an enormous savings in compliance costs.
"There is already a movement afoot to standardize state and local sales taxes; the FairTax can realistically be expected to accelerate that trend."
If I understand this correctly, I must say that I am 100% opposed to this standardization. I would prefer that the states run their own business and allow me to chose which state is more deserving of my residence. That is one major improvement that can come about as a result of the NRST, increased competition for corporations and residents among the states. If your saying that the NRST could be a tool to standardize the state's tax policies, then I have to disagree with that aspect of the NRST.