There are countless miles of boundary hedges in between quiet rural fields. So why choose a roadside hedge instead? It's not as if their songs can be clearly heard above the traffic much of the time. Perhaps they like the ready pickings of the insects knocked down to the bare asphalt by passing vehicles? It is commonplace to see a whole variety birds foraging on the roads in the warmer months. Usually solitary wagtails, in particular, can always be found on any stretch of rural road or lane in summer.
Too busy on a project to go for a ride today.