Who has got the answer to the Lamp Post mystery?

We must assume that our street lighting here in Neath is being renewed as a power saving exercise - however, readers are baffled.   Why change the whole lamp-post?   Why not change just the lighting fitting?

 

 

 

 

 

 

 

 

 

 

 

Just change the lighting head? It can be done in less than 10 minutes, the proof is on the video below: