One MAJOR problem that this article doesn't address is the fact that sales taxes vary widely, even within a state. Where I lived in Arizona, there was State sales tax, county sales tax, and city sales tax. Just creating a database to support EVERY municipality in the country will be a nightmare for business.
In Canada, they have the HST, "harmonized sales tax" a.k.a. "Harper's shi**y tax" which is 15% regardless of where you live or where the company is located on EVERYTHING you buy from gasoline to McDonalds. The money is collected by the federal government, BUT doesn't go to the federal government, it goes to the proper province and community. This is how Canada pays for their healthcare.