Why so many street lights?

Every time I drive past Exeter (UK) on the M5, I am struck by the amount of street lighting there is at Junctions 29 & 30. Why?

A few months ago, when the road was being repaired and upgraded, all the lights were removed. During this work it was much safer, as it became very easy to see vehicle headlights from a long way away as they joined the Motorway or, conversely, if you were joining the motorway, you could see if traffic was approaching your junction.

This made it much safer! It also saved the energy required to power approximately 140 sodium lamps!

Living in a rural area, with lots of very narrow, winding lanes, I have always found it easier driving at night because of this effect of seeing the headlights shining way before the vehicle was close to you.

I would love to hear what others have to say about the amount of totally superfluous lighting, wasting energy as if there was no damage to the environment by so doing!