Re: UK plc should share some of the blame...
When I was contracting I saw no point in trying to simultaneously do my already busy job and take on the frustrating task of trying to train my cheaper and much less capable replacement, knowing they would cock things up and place the blame on me as I would not be there to prove otherwise.
The line I used to take was that I would have to document the hand-over, as a chargeable consultancy item that was not already specifically identified in the contract, and that hand-over could only be to a suitably qualified person who could prove they had the same or better tech qualifications than me; otherwise it would be professional training, which I was not contracted to do. Also, I used to keep a day diary to show what problems had been tackled and would say "let's pick an example and see how well they they deal with real issues".
Documenting this would only sometimes make the contract last a bit longer, but it covered me and raised the blood pressure of those trying to take advantage by doing things on the cheap. Those employers wanting to do things properly could understand my rationale.
Basically I try to adopt the attitude of a contractor I met a long time ago when I was first a permie; he said "I don't suffer from stress, I'm just a carrier'.