Coffee shops were the retail pioneers of Wi-Fi, flipping the switch to lure customers. But now some owners are finding that Wi-Fi freeloaders who camp out all day nursing a single cup of coffee are a drain on the bottom line. That shift could gather steam now that free Wi-Fi is less of a perk after coffee giant Starbucks stopped charging for it last month. "There is now a market niche for not having Wi-Fi," said Bryant Simon, a Temple history professor and author of Everything but the Coffee: Learning About America From Starbucks.