Tri-county economic development chiefs, adhering to Amazon’s rule of just one bid from any region, are wise in jointly pitching the expanding giant on a headquarters site. Multiple bids would doom all three counties. Even united, it’s a hard battle with more than 100 bidders from across North American, some of whom will give away the store. We surely won’t. In eight detailed pages, Amazon gave regions until Oct. 19 to pitch a second corporate home, with plans to pick a winner in 2018.