Who wrote the software? VW or Bosch? I'd say it was Bosch.
It's entirely possible that Bosch did it off their own bat and offered the solution to many manufacturers as a way of beating US emissions regulations. Maybe it just isn't possible for Bosch to set up a fuel system to deliver what the US require in terms of emissions so they wrote the code to fool the test. You can be sure that VW won't be the only ones who took the option if offered to them.