What a grease ball

The American automakers must have REALLY felt compelled to stop oil leaks sometime in the late 80s. GM went to a different type of valve cover on their small block "corporate" engine and Ma Mopar went to the "Magnum" series with the thicker valve covers and a 10 bolt arrangement. I don't know what Ford did because I never owned one AND I like women and Women don't like to wait for tow trucks.
My 2007 Ram 1500 5.7 Hemi has 340,000 miles and ZERO leaks.
What motivated the improved sealing in these engines? Was it consumer demand? Was it a matter or warranty costs? Maybe the EPA mandated it?