1928's "[The Revolt of the Pedestrians](http://blog.worldswithoutend.com/2018/02/reading-the-pulps-4-the-revolt-of-the-pedestrians-by-david-h-keller-m-d)" by David H. Keller is _the_ forerunner of this type of story. Humanity has split into two subspecies: "Automobilists" and "Pedestrians". The motorists have become so dependent on their "autocars" that their legs have atrophied. 

The motorists have the upper hand at the beginning of the story:

There is a scene with a little boy and his father at a museum exhibit of pedestrians, who, being fair game for being run over, have been nearly exterminated.

>Then came the final law providing for the legal murder of all
pedestrians on the highway, wherever or whenever they could
be hit by an auto.

The title should tell you the situation doesn't stay that way.

Keller was a eugenicist and a racist, but as long as you can maintaim suspension of disbelief the story will hold you. 

([full text here](https://www.fadedpage.com/showbook.php?pid=20190404))