I can only assume we work for very different employers then! As I've said before, at our shack anybody dispatching a train with several hundred punters teetering on the edge of the platform would he held entirely culpable if one of them ended up down the gap. And any Guard closing doors on people would also be in for a pretty hard time.
On LUL both of these things appear to be standard practise.
I can assure you that LUL drivers take the safety check very seriously. It's something that is observed in competence assurance, and no driver worthy of the grade would knowingly depart a platform with people in an unsafe position. The safety statistics are there to back this up - dragging incidents are extremely rare, as are people coming into contact with trains leaving a platform. Most platform/train interface incidents are either people getting caught in closing doors when running to board a train or alighting whilst doors are closing, or are alcohol related mishaps.
LU has gone to lengths to improve platform/train safety in recent years. From yellow lines on platforms to selected platforms being staffed with specially trained staff at busy times, as well as working groups tasked with identifying safety improvements, reviewing incidents etc.
I have certainly seen mainline trains close doors whilst people are attempting to board, London Bridge platform 6 was a classic example. Likewise, a morning peak at many mainline commuter stations in the London area will see trains dispatched with people standing near the edge. At Hitchin, for example, regular commuters know where to line up on the platform for their door, and for certain services will arrive up to 20 minutes early to secure their spot at the platform edge, letting other services go in the meantime. They certainly don't stand back from the edge as that risks losing the spot, and there's no staff on the platform to keep an eye on things. All a symptom of an ever more overcrowded railway and country unfortunately, but passenger behavior doesn't change depending on whether it's mainline or metro- the self-same people lining up at Hitchin will, 45 mins later, be doing the same whilst attempting to board an Underground train at King's Cross or Finsbury Park.