Comment by AshleyGrant

Because, for the most part, we aren't doing damned thing about it. "Rolling coal" is inherently a very public act of law breaking, but I doubt a single person has ever been pulled over by any American cop for it. The EPA and certain states were trying through other enforcement mechanisms to fight it, but with Trump in office, it's basically encouraged to "delete" your Diesel emissions equipment if you aren't in commercial operation.