Mark Schoeff Jr. arrived in Beijing last week with a wallet full of useless plastic. The veteran Washington correspondent — accustomed to navigating the world’s thorniest financial regulations — found himself stymied by the very systems he reports on: His American credit cards were incompatible with China’s dominant digital-payment platforms. “It was a perfect, frustrating example of the fragmented global systems I cover,” Schoeff told Global Business Journalism students at