The interesting part in that last post is found in the last line.
From Wikipedia: Due to its preexisting standards and particularly severe motor vehicle air pollution problems in the Los Angeles metropolitan area, the U.S. state of California has special dispensation from the federal government to promulgate its own automobile emissions standards. Other states may choose to follow either the national standard or the stricter California standards. States adopting the California standards include Arizona (2012 model year), Connecticut, Maine, Maryland, Massachusetts, New Jersey, New Mexico (2011 model year), New York, Oregon, Pennsylvania, Rhode Island, Vermont, and Washington, as well as the District of Columbia. Such states are frequently referred to as "CARB states" in automotive discussions because the regulations are defined by the California Air Resources Board. The EPA has adopted the California emissions standards as a national standard by the 2016 model year and is collaborating with California regulators on stricter national emissions standards for model years 2017–2025.
Who-ever it was that said "car companies simply set up all cars to the stricter standard of CARB"......technically incorrect for the question asked in the OP.......but starting with model year 2016.......it would be a correct statement.....not by choice but rather by way of the new standards adopted by the Federal Authorities..