An obvious geographical divider does seem to increase the natural inclination of many people to stay within their known area unless given a specific reason to venture out. Canberra has a similar effect with lake Burley Griffin and people being less inclined to venture southside from northside (and vice versa).
You're certainly right that the way I did it in school felt rather performative and didn't leave me with positive impressions of the books I had not read previously. I'm not going to say there's no purpose in trying to understand the meanings/symbolism in a work but it's not going to make a good impression on someone if that's their first introduction to the book - or worse their introduction to reading books in general.
I've no substantiation for these guesses but one thing that comes to mind is that boys were more likely to get into computers in the early eras of tech and that time sink could lead to them being less likely to build the habit of reading. TV is another possibility, Gen X was the first to grow up with TVs being widespread and boys probably spent more time on that.
My wild ass guess would be that it's a gauge for measuring water levels, with the upper opening part being a scale to read a marker that moves up and down the pole.
Does it line up with anything on this map of Brisbane water/sewer infrastructure? That map seems likely to give you at least an idea of what system it's associated with, and might even give more of a clue about the purpose of this specific point.
Out of the four smokers I regularly work with three of them have found shops that sell black market tailormades and the other buys pouches off some internet site which is almost certainly also dodging tax. It doesn't seem like they're having any hassles finding and buying these things and with black market apparently being about half the price of cheap legit cigarettes you'd have to be pretty firm on your principles to take the financial hit.