It's only properly dark for a short time towards the end of term. Streets are lit, bus stops are lit, buses are lit, because it's so early, there are plenty of people around and there will be all the other schoolkids (and school staff) travelling by public transport at the same time. Where I work, there's usually a cluster waiting outside the gates by about 7.10am, just as the majority of staff are going in and the numbers increase steadily until they can go into the canteen for breakfast - the wait outside is valuable mobile phone and chatting/socialising time for them.
I think aged 11-12, they're also a bit past the point of 'if a man comes up and asks you if you want to come and see his puppies, you must tell your Mummy or a policeman'.
Just by virtue of living in similar areas, kids tend to form groups to travel together. I was properly antisocial at school, but I was never short of somebody to walk with, clubs, early starts or not, from the first day of Year 7 to the day I left - and that still holds as true for school kids now as it did then.
The only people I have encountered IRL who maintained that 'people' (they meant women) shouldn't be out after dark unless it's a dire emergency - which meant not working fulltime, not shopping after work, not seeing friends or having GP appointments/anything else because it was before 8am or after 3.30pm - were either abusive or in abusive relationships.