They share some blame, too, but I'm willing to guess the problem predates the unionization of the city's workforce. I'm not sure when Detroit's city employees were unionized, but it was probably in the 50s at the earliest. They no longer needed the job by the end of WWII, if not earlier.
Does the city have a working blacksmith, fabrication or welding shop that repairs equipment?
The article sounds like the guy is working, just not on horses.