Some of the huge guys like Rockwell and Siemens may offer integration services; I'm not 100% sure though.
But I'm guessing it's mostly because system integrators are qualified in a way a software company isn't. The scope of a project that an integrator might take on can be vast and the SCADA software is generally only one piece of the equation.
But I'm guessing it's mostly because system integrators are qualified in a way a software company isn't. The scope of a project that an integrator might take on can be vast and the SCADA software is generally only one piece of the equation.