They didn't see it coming around because they thought it would be coming around earlier in the day and on a different track.
And when they came around the bend, they were singing. "What were they singing", I know you query. They were singing "She'll Be Coming Around the Mountain."
That so many others seem to do what they wish and avoid consequences would belie any concept of karma. It is pretty shocking when someone occasionally gets his comeuppance.
because they never thought it would hit them in the face.