Here's a scenario that explains this quite well..
A little boy and his father were waiting for the bus when the little boy saw two dogs crossing the road. The dog at the back was mounting the dog in the front.
"Dad," said the little boy, "look over there. What are those dogs doing?"
The father had to think of something quick, and he told his son that the dog at the back had got sore paws from walking all day and the dog at the front had kindly allowed him to put his paws on her back while they crossed the hot road.
"Just goes to show, " said the little boy wisely, "you help somebody out and you still get screwed"
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When I left the hospital in JHB to come to London, one of the superintendents (a very elegant, senior lady) asked me what I expected the major changes to be, with regards to working in the UK instead of SA.
I said "I won't have to do this anymore" and I shuffled down the corridor, holding my ankles. She laughed about it, but she got the point too.
Of course the same thing happens here in the UK, but it seems to be a bit more civilized, in that you have advanced warning of the deed and there are limits to how badly they can screw you over, unlike SA where at the moment a white male of working age is automatically screwed over, regardless of his expertise. And there they screw you over so that you get nailed financially AND you can't advance in your career AND you end up facing increased odds over personal safety.
There have been several attempts by agencies and health professionals here in the UK to take advantage of me, but I have always found a way to not get abused (although the theft of intellectual property is a continuous threat). But in SA it is much more difficult to get satisfaction when a deal goes sour.