Points all taken remoak. You're right of course in that we should always err on the side of caution, and I can't think of any scenario in a million years where any instructor with a brain would authorize a night VFR XC over the King Country.
And yet completely avoidable accidents keep on happening, even when a good conscientious instructor has applied the nth degree of safety precaution. So what goes wrong?
I know there's three or four of us on the thread who were lucky enough to train under Gordon Vette in the early '90s, and remember what a tight ship he ran, his whole being was devoted to passing on his immense airmanship to his instructors and students ... and yet on his watch, a CPL student killed himself and an innocent passenger in beautiful weather in one of the most immensely stupid acts in the history of kiwi GA. Bad things can happen even to good instructors.
What I should have maybe said was, that the instructor uses his own airmanship to assess the student's solo ability and signs them out on an exercise suitable for their level of ability. The student places their trust in the instructor not to send them into anything dangerous, but it's a two way street, we also place our trust in the student to use what skill and judgment they have when they're out there and not do anything they're not authorized or trained for or that they know might lead them into trouble.
Every single flight has the potential for tragedy if that trust isn't taken seriously by both parties. I would suggest unless facts prove otherwise, that the breach of trust in this case occurred at the student rather than the instructor end of the bargain.