The coalition organized by the Retailers Association of Massachusetts is right in its campaign to force Amazon and other on-line leviathans to pay sales taxes on their business here. Amazon obviously wasn’t the totality of Borders’ problems. Borders was late to e-commerce, and the move to e-books on the Kindle and Nook obviously hurt as well. And yet, all that said, Amazon has a substantial advantage in not paying the state’s 6.25 percent sales tax on its Massachusetts sales.