I read in a New Zealand car magazine once that some premium car makers fly journalists to exotic locations and give a them a very pleasant few days looking after them. They drive cars around and go home to write nice things. It was stated that if you came back and were not positive in what you wrote, you didn't get an invite for the next model release. Car maker gets its way.
When it comes to emissions testing in Europe, while testing is at times done by government authorities in the US, that is not the case in Europe. Car companies in Europe 'shop around' for agencies to test their cars. How favourable the test turns out depends on whether in future that agency gets more work from the car maker or not.
I am I Einstein, or can anyone work out there is a conflict of interests in the European testing? No need to fit gadgets to the car in the EU as the tester has all sorts of tricks up his sleeve to get the result the car maker wants. When a German car magazine says that a certain vehicle's diesel engine was more than 11 times over the legal emissions requirements in Europe, there was no device fitted to affect the result. The test system can make that happen. Car maker gets its way.
So politicians who talk of cleaning up the cities are no doubt pushing that fair testing is done, right? Erm, well, possibly. There is no way governments would work behind the scenes to see that the 'high employment, revenue earning, car industry' is allowed to use a loop-hole riddled testing system to its advantage. Of course not, how silly of me. I must be getting cynical in my old age. Einstein I am not, but then, do I need to be?