Let me first say that I agree that the OP overstated the case: many 14 year olds are perfectly capable of making the right judgment call in cases such as this. However...
and any 14 year old that is capable of hacking a tram is intelligent enough to have picked up on society's general distaste
Intelligence has little to do with the ability to empathize or with social skills in general. Yes, an intelligent person with an autistic disorder may be able to mitigate the consequences of his disability by learning the required responses. However, a fourteen year old will never have mastered that technique yet and some never do. And no, I'm not claiming this boy has an autistic disorder; what I am claiming is that many such people, myself included, have traits that much resemble those of people with autistic disorders, to the point where I often feel like I'm responding from knowledge to social situations, rather then from feeling. And I remember a particularly (in hindsight) stupid thing I almost did when I was a 12 years old, because I had no regard for the people involved. Nor for the consequences for me BTW. That is one important point people are overlooking: the boy may also have failed to realize he could go to prison for this. So busy tinkering and playing that he lost sight of the outside world.
What's more, if he was aware enough to study and record the tram system then he was aware of the danger
Rationally knowing something could go wrong and linking that to actual people actually suffering is a huge step for some people. Eichmann is probably the canonical example. Yes, he was liable and he was rightfully held accountable. That doesn't necessarily mean he was guilty in a moral sense. Can you be guilty of failing to consider consequences to other humans, if failing to consider those consequences is your natural way of being? I'd rather call it a mental disability than criminal intent.
and any 14 year old that is capable of hacking a tram is intelligent enough to have picked up on society's general distaste
Intelligence has little to do with the ability to empathize or with social skills in general. Yes, an intelligent person with an autistic disorder may be able to mitigate the consequences of his disability by learning the required responses. However, a fourteen year old will never have mastered that technique yet and some never do. And no, I'm not claiming this boy has an autistic disorder; what I am claiming is that many such people, myself included, have traits that much resemble those of people with autistic disorders, to the point where I often feel like I'm responding from knowledge to social situations, rather then from feeling. And I remember a particularly (in hindsight) stupid thing I almost did when I was a 12 years old, because I had no regard for the people involved. Nor for the consequences for me BTW. That is one important point people are overlooking: the boy may also have failed to realize he could go to prison for this. So busy tinkering and playing that he lost sight of the outside world.
What's more, if he was aware enough to study and record the tram system then he was aware of the danger
Rationally knowing something could go wrong and linking that to actual people actually suffering is a huge step for some people. Eichmann is probably the canonical example. Yes, he was liable and he was rightfully held accountable. That doesn't necessarily mean he was guilty in a moral sense. Can you be guilty of failing to consider consequences to other humans, if failing to consider those consequences is your natural way of being? I'd rather call it a mental disability than criminal intent.