Why Didn't This 1930s Cow-Catcher For Pedestrians Ever Catch On?

Were the roads of the 1930s littered with fallen pedestrians, lying prostrate after auto collisions, fainting bouts or rapid-onset naptimes? One might think so to judge from this hoary concept for a "roller safety device," which the divine site Modern Mechanix notes will "literally sweep a fallen pedestrian before it and thus save him from being crushed to almost certain death beneath the heavy wheels."

The highly suspect invention, appearing in the March 1931 edition of suspect-invention treasure trove Modern Mechanics, is meant to alleviate that most tiresome chore of Great Depression motoring: the removal of tangled-up plebes from your factory-polished axles and gears. Well, the way it's phrased in the article makes it seem like it's a pedestrian-safety feature. But a rational consideration of this device would indicate it'd have the same effect on a human body as a cannonball would on a wedding cake.