They need to make a decision are taxes imposed based on the location of the seller (the online company's location or brick and mortar location) or the location of the buyer (the online or offline buyer).
If they are going to require all online companies to collect sales taxes then all the offline companies need to tax based on the home of the buyer rather than the location of the store.
"Today the government has announced that the free speech zone covering the entire country will be gitmo. Have something you want to protest go to the tip of Florida and keep going south. Don't forget your kickboard."
In some book, hopefully fiction, I read a while back to avoid these types of problems with domestic spying the US government and UK government spied on the other government's citizens and shared the take.