Electric vehicles have struggled to gain mass appeal in much of the world despite the fanfare surrounding Tesla Motors, the world’s best-selling brand of plug-in cars last year. Drivers worry about prices, comfort and what happens when a battery expires in the middle of a trip. But in Taiwan, scooter vendor Gogoro doubles its sales every year largely because of a widespread battery exchange network supported by a central government that’s keen to control emissions. Gogoro designs what it describes as ride-able scooters as well as engines for other brands, filling what the chief executive officer calls earlier market voids. “People say we’re the two wheels of Tesla, and in some ways, we are,” CEO and co-founder Horace Luke said. “We do a little bit of everything.” The company, which launched in 2011, first had to prove that it could all be done. “Nobody could believe that an electric vehicle could …