We had a power failure here recently, and someone actually did that.
They ran the cord across the road surface in their neighbourhood :-) Didn't put a ramp over the cord or anything to protect it.
It seemed to survive a couple days of road traffic (40km/hr max) with no problems.
It was one hell of a long run of extension cords in series.
I didn't see any other examples like that.
At a rough density guess, maybe one house in forty had a genny. So we're still not ready for emergencies here.
Paul