Workers at RDU1 and other facilities told CNBC that Amazon is increasingly using digital tools to deter employees from unionizing. That includes messaging through the company’s app and workstation computers. There’s also automated software and handheld package scanners used to track employee performance inside the warehouse, so the company knows when staffers are working or doing something else.

“You cannot get away from the anti-union propaganda or being surveilled, because when you walk into work they have cameras all over the building,” said Medelius-Marsano, who is an organizer with CAUSE. “You can’t get into work without scanning a badge or logging into a machine. That’s how they track you.”