This is a very old issue, literally going back over 100 years, with a new name and more attention because the internet is involved. Mail order companies such as Sears, Montgomery Wards, Beans, etc faced off with the states over the sales tax collection issue during the days when catalogues were paper and delivery was by horse drawn wagons.
The arguments were the same then as they are now. The states wanted the retailers to collect the taxes from residents of their states regardless of where the retailer was located. The retailers did not want to deal with 50 (or even 48) different sets of sales tax rates and regulations. The states refused to standardize and the retailers dug in their heels. The volume in those days simply was not enough to make the fight worth the effort. So both sides let it drop.
Today the dollar amounts are much higher. So the battle has been reengaged with new terminology. But it is still the same basic issue.
Another point to keep in mind is the degree to which this is a back door gift for current large online retailers. There are major IT cimplexity issues which must be overcome required for retailers to calculate, collect and transfer sales taxes for each of the 50 states with different rates, different regulations etc. This is not a problem for large well established retailers but a significant barrier to entry for small mom and pop shops trying to sell on the internet. The Senate bill essentially cements the 1 percent of very wealthy internet retailers in place while freezing out the 99 percent of small businesses who would like to grow larger but simply cannot afford the computer system necessary to comply.