My take: union organizers are not Amazon employees and are not allowed on Amazon property. The only place organizers are allowed to interface with Amazon employees are public roadways where Amazon employees exit their workplace. Amazon made the green light longer on the traffic light exiting the Amazon workplace so organizers would have less opportunity to speak with employees. Employees would naturally be anxious to get away from work quicker and less likely to speak with organizers and stall traffic on a green light.