Many don't anymore. Same story as timing belts. There was period in the late 90s through 2010s where they were standard until the OEMs realized nobody actuall

Many don't anymore. Same story as timing belts. There was period in the late 90s through 2010s where they were standard until the OEMs realized nobody actually changes them and they generally become nasty to the point where they make the air dirtier. Now a lot of cars are omitting them again.