Florida Georgia Line came out of nowhere in 2012 to become the biggest country group of the new decade. The vehicle of their success was "Cruise," a slick, shimmering ode to the wide-open road that became an unkillable crossover hit in 2013 and, eventually, the biggest country single of all time. They'd lose that record to Sam Hunt, whose "Body Like a Back Road" took the country crown in 2017, but they regained it the next year when "Meant to Be," their duet with pop singer Bebe Rexha, stayed at the top of Billboard's Hot Country Songs charts for 35 weeks. "Meant to Be" wasn't...