Mail-order was never the big business that e-commerce has become today. Even in the days of the Sears Roebuck catalog it didn't compare, thanks to the faster ordering, shipping, and tracking the modern age offers.
E-commerce is finally getting taxed because it's too big to stay under the radar; the peoples of 45 states have decided they want to fund their governments with sales taxes, and those taxes need to be collected.
Still, there is nothing to justify singling it out and not including all mail/phone orders, no matter how comparatively small the non-Internet orders are. The law should apply to all or nothing with the justification that e-commerce has made mail order too big to ignore. Sure, Best Buy isn't complaining about HSN or Fingerhut or whatever "As Seen on TV" product is currently being advertised on TV, but making every kind of business subject to specific laws and exemptions only complicates the matter further. The simplest target is to target ALL mail order sales for tax collection including Internet sales.
Instead of Best Buy complaining that Amazon has an unfair advantage, soon Amazon will be complaining that the manufacturer-direct parts and accessories listed in the printed product manuals is unfair. I can see it getting worse: I buy a Playstation 4 from Amazon and it comes with a catalog from Sony for controllers, cables, game subscriptions,
and games. Let's imagine that I ignored digital delivery and ordered physical games and stuff. Every controller, game, or BD movie I buy comes with a newer mini catalog promoting newer/upcoming releases at the same price but minus sales tax.
In the early '90s, I noticed that my Super Nintendo had an S-VHS cable available direct that wasn't sold in stores. I called the same number (1-800-255-3700) to order my replacement Gameboy screen cover and my replacement Gameboy Pocket battery door. I continued using it for everything from refurb games/hardware, Virtual Boy stands, Gamecube component cables, empty game cases, Gameboy Advance SP audio adapter, Play Yan, and Gameboy micro link cable, etc. None of those things were available retail (well, unofficial knock-offs sometimes were), but the telling point is that a lot of the stuff they offered that I didn't order was. I do recall ordering the Gamecube Broadband Adapter directly because the stores were out of stock.