IIRC, many such machines were originally controlled by OS/2. With numerous of the companies "stuck" on an OS/2 solution for such, and various having the need to replace older failing boxes, it only makes sense that they support eCS. They probably continued from and expanded upon their original Generation 8 (and earlier) implementations.
For instance, their ancient GSM1 version from 1999 or earlier... which ran on OS/2.
There are a few other big companies "stuck" in similar scenarios. The amount of specialized machinery that OS/2 used to (and in many cases still does) control is whopping... elevators, fire control systems, traffic monitoring systems, metro payment systems, metro train systems, assembly line systems, older z/OS mainframe systems (yup, onboard OS/2 based system for the system management) and numerous other vertical markets...