>>3099984>>3099982>>3099980>>3099977Eggleston was famous for his use of color and photographing incredibly ordinary and typically uninteresting looking scenes. He's one of the first to use color in a way that would help bring it to the mainstream, because at the time the vast majority were sticking to black and white and felt that color was too commercial, not artistic.
The red cars help because they are warm and fit the color palette of the scene. If they were any cool or neutral color they'd disturb the scene and draw too much attention.
His stuff is clearly not everyone's cup of tea. In fact, he along with other photographers in the "New Topographics" movement were infamous for creating uninteresting photos and initially they received a lot of backlash. I think Ansel Adams even came out and basically called Eggleston's photography garbage. Regardless, the new topographers inspired a whole new genre and they are what informs the images you see of mundane looking scenes. The point was to try to find beauty within banality, by using abstract compositons and pleasing color palettes to engage the viewer rather than striking scenes of landscapes or shocking photo journalistic works.