Toyota is retiring the fabled “andon cord,” the emergency cable strung above assembly lines that came to symbolize the built-in quality of the Toyota Way and was widely copied through the auto industry and beyond.
Toyota’s rationale for moving to buttons, according to the article, is the desire to clear the overhead space. Another advantage, not stated in the article, is that the alarm from a button is more location-specific than from a cord.
Another reason to use a cord was that you didn’t have to change it when you rearranged the line, whereas relocating buttons required rewiring. But the wireless button technology has made this a moot point.