Ahhh just like the late '70s and '80s with gasoline engines. Emissions robbed all the power, cut fuel economy and the engines ran terrible with high maintenance cost. Many just ripped the emission equipment off.
Diesel has been exempt for far too long and is just going through the same growing pains the gassers did 40 years ago.
Lots of gassers were sent to the junk pile when actual emissions testing was implemented and modified vehicles had no cost limit to bring them back to OEM condition or registration was denied. And yes I was a licensed inspection and repair technician back in the '80s. People were angry when their Corvette was suddenly worthless.
I remember an Aston Martin that came in and it was way out of adjustment. The fuel injection was beyond us so we sent him to his specialist. When he returned for the retest he mentioned how much better the car actually ran when tuned properly. Passed with ease and all was good.
This diesel thing is going to cause some heartache but will be much better as we make progress and people comply. The air is certainly easier to breathe today than it was 40 years ago.