It is much simpler than an ICE... Because science. The problem with the CR reliability is there is no weighting scheme to each specific issue. For example, a screen freezing is a reliability issue that is weighted the same as an S class transmission failing. With the model S especially in the earlier years and for some reason a batch of 2014 models (made in 2013) had an issue with DU's making noises. The other problem is some of it is Tesla's fault for overzealous servicing. They'd replace a DU if they felt it was making noise.
Excellent point, the order of magnitude difference between a broken sunvisor versus a broken transmission is immense .
It seems to me the DU issue is forever behind them, any information on that?
Elon mentioned the objective of a 1 million mile drive train life.