The Automotive-Oil Consortium of the 1990’s demonstrated that using natural gas in vehicles released more reactive chemicals than gasoline or diesel in certain climates/altitudes than ethanol/methanol mixtures - as I recall - so the California automotive research board learned that fuel and engine design wasn’t an all-areas fix or cure, but region specific.
But we’re not smart enough for that, so one size fits all - the public image size!
Do you have a link for more info?