I work for a company that makes Diesel engines. Only answering the engineering question that was raised above, not stating any opinion on the validity of the regulations...OK legitimate question here; what is less pollution and better for the environment - 200 gallons of diesel and 20 gallons of DEF or 125 gallons of diesel, doing the exact same identical work before and after. ? This is the literal, day after day results my friend got.
You're gonna have to come with some pretty good arguments to convince me that making, transporting and burning an extra 75 gallons a day is the "environmentally friendly" way.
BTW no smoke either. Rolling coal is for idiots, for the most part. Not that I haven't done my fair share.
Basically, the engines of today produce well under 1% of the particulate and NOx emissions of the previous engines (ignoring Carbon emissions). The math proves that you would then have to burn more than 100X the fuel to produce the same pollution.... so from the EPA view, forcing you to burn 2x the fuel for the same job equates to better air quality.
Hope this helps clarify part of the issue.