I suppose if there's an incident blocking a lane or more the emergency services will have the option of driving from the opposite direction to the tailed back traffic, but is it not common for the whole carriageway to be shut for the Air Ambulance if it's that serious anyway?
But there can be many miles between junctions and inching through tailed back traffic even from the nearest junction to an incident presents a serious delay over running down the hard shoulder. The emergency services cannot approach from the opposite direction and run against the flow of traffic on a motorway, until the Police have already reached the scene from the conventional direction, closed off all lanes, and confirmed that there is no traffic between the scene and the next junction, which takes a significant amount of time.
As for air ambulances, generally one won't be dispatched until a land ambulance resource has already arrived on scene and deemed one to be neccesary and confirmed there is an appropriate landing site for one at the incident. They are also an extremely limited resource in the first place, generally with only one per county, so they're not always available when needed. Very few air ambulances can fly/land during the hours of darkness, nor can they fly/land in the fog/heavy rain when most serious motorway incidents occur. There's also no air fire engines to my knowledge, so the fire service would still have to push their way through tailed back traffic if someone is trapped and requires cutting from the wreckage. Due to the size and manoverability of fire appliances all lane running potentially presents bigger delays to the fire and rescue service than to the ambulance service.
Absolutely correct.
Getting a designated service to secure the scene can be done from the opposite carriageway, but then you have both directions at a standstill. I have known Fire to stop adjacent to an incident, but on the other carriageway, and work over the barrier, but most of the new sections have a concrete barrier which is higher and wider.
As far as breakdowns go, tyres and fuel (or lack of!) account for a significant number of stops.
It is actually quite rare to see a broken down classic car.
A further concern is that the AA and RAC will not deal with a vehicle which is in a 'live lane'. Not sure about other breakdown organisations. I have yet to see what their policy is with regard to these new situations.