That was my thought, the Western Talisman accident at West Ealing is one reason why, something as simple as an improperly locked maintenance door killed 10 people, I would imagine sensors that would make you aware that a battery cover is loose on a train might not exist and if they did, you would need quite a few of them on even a 4 car train.I agree, the maintenance guys aren’t the ones driving the train
As with West Ealing, there are so many occasions with aircraft accidents where maintenance has been done over 2 different shifts or one job has been carried out by 3 or 4 different people, so things have been left either half done or parts not fastened securely, the various Aircraft safety boards have made sure that this sort of thing shouldn't happen in future, an old colleague used to service the Jaguars for the RAF and then he went to work on the Omani ones, he said that after he did any work on one, if it went out and never came back, he would rack his brain wondering if it was something that he missed.
Drivers/Guard/Train Manager should be the ones who check the trains beforehand, it is all well and good being told at the depot that X train has already been checked, it is fine, take it out, but if something was to fail, causing an accident after that that could have been spotted before taking it out, would the RAIB not find fault with the driver if he had not checked the train before taking it out.