All roads have the same problem.... bad drivers. At least with a dedicated hard shoulder, you have the relative safety that under normal circumstances, the lane is not used by anyone unless they are stationary (apart from entering and rejoining the main carriageway). With the 'Smart Motorways', that safety net has been taken away, and you are now reliant on the technology to close the lane quickly. However, 'closing' a lane is just putting a red cross on the gantry's above the lane. You are then still at the mercy of drivers a) knowing it is illegal to travel under a red cross, therefore moving out of the lane and b) actually bothering to pay attention to the red crosses, they see a clear lane and think 'fuck it, nice and empty, I will fly down there and save some time'
Not everyone will feel they can safely exit a vehicle with traffic flying past them either, so just telling them to head for the trees is a little naive.