The Coroner can't make anyone do anything. They simply investigate deaths and make recommendations as to how similar deaths could be avoided in the future.
It's an incredibly powerful court of law in its own right though - they can recommend charges to the DPP, they can have you de-registered if you are a professional person dealing with the public. I personally know of someone who was called before an inquest in their professional capacity who was torn to shreds over the death of a client whom she had absolutely no control over... you'll have to PM me if you want the details because I don't feel it's appropriate to discuss on an open forum. But needless to say they can rip you to bits if they think there was anything you could have possibly done to prevent a death, even where the death was by suicide, stupidity or mis-adventure. And they regularly name and shame people/organisations in the media.
That's why Metro/PTV were pressured into making this change to Comeng doors - initially they were told that they would have to retrofit all Comengs with solenoid devices that actually locked the doors on closing but that would have cost tens of millions for a type of rolling-stock which (frankly) doesn't have a long time left on the tracks anyway. So the change in door handles was a compromise that doesn't quite work but nevertheless cost a lot less than the overkill solenoid idea.
If someone wants to force open a train door and hang their head/body out at speed then it's Charles Darwin's desire that they should be punished for that action, possibly removing them from the gene pool. The Coroner and their ilk seem to think that everyone, regardless of the inherent stupidity of their risk taking behaviour, can be saved from themselves. Nanny state, pure and simple.