Yes you can control them.
I thought it was the exact same thing as "factory maintenance units". On closer look the cost of maintenance products is 2X the of the raw material FMU used.
You can buy low quality FMUs but then your products will be less valuable.
You can build corporations and then not upgrade them.
In many cases the increased revenue from high quality and lower salaries from high effectivity will pay for the cost of maintenance.
Paying high wages increases output. High wages are nice because you get income taxes. High quality raw materials and higher wages will dilute the cost of the FMUs.