Transit officials in Washington, D.C., are concerned that their next subway cars might be bugged. Cybersecurity experts wonder: If a state-owned Chinese company wins a contract to supply the city’s Metro system with new cars, might they come with devices installed to surveil U.S. public officials? Metro officials will try to engineer their contract to prevent all this. But why can’t they solve the problem by simply buying American? The answer is this: No U.S. company makes them.