Over the last decade or so, we have noticed a change in crow behavior, at least in our neighborhood. When a crow was gleaning by the wayside on our local streets, they used to fly away as a car neared. Then, they started hopping to the curb. Now, most of them just back up a yard or so when a car passes. Any observations or comments?
The American Crow (and its cousin the Common Raven) are very intelligent birds. The American Crow is one of the most adaptable bird species.
I'm certain they have learned to avoid cars by simply moving off the road rather than flying away, as they are capable of learning to solve fairly complex problems. They know that cars simply pass. Cars generally aren't trying to hit them and they typically travel in predictable, straight paths. So, the crows know that they can get out of the way and wait until the cars pass before resuming feeding on whatever they have found in the roadway.
This conserves valuable energy the crow needs to survive, especially in colder times of year. It's expensive physiologically to keep flying away every time. If the cars don't generally hit crows, then it's not necessary to expend more energy than is necessary to avoid being hit.
Here's some interesting research on crow behavior and learning published in Audubon Magazine. I hope this response helps provide some context to your observations.