Just like in Victoria, the pure excess of these signs, with their attempts to regulate public behaviour in intrusive detail, creates confusion, because one is not used to being regulated like that. It feels like either (a) the signs are being written in a foreign kind of English, assuming a great deal of local knowledge, or otherwise one sinks into a feeling of fatigue: maybe (b) it’s better not to try to use these spaces at all.
For example, what could it possibly mean that “the playground is designed for children aged 2 to 12 only / Children must be supervised at all times.” What kind of regulation is that, what does it actually proscribe? Are people older than 12 allowed on the playground only as long as they supervise other children? What are we allowed to do, within the limits of our supervision? Are adults allowed in, if they’re not supervising children? If they are, what is the point of the sign? Who is actually banned? Is it to make sure nobody older than 12 tries to play? Are 13-year-olds allowed in if they’re supervising younger kids, or are they just blanket-banned until they have kids of their own? Are 12-year-olds allowed to hang out without playing? Is a 12-year-old allowed to supervise a 6-year-old, does that count as supervision? What kind of regulation is that anyway?! Who in the world cares? And what are the sanctions? Who is even capable of policing that amount of behaviour in an entire playground?
And yet, the tone of the Brisbane signage is slightly different to Melbourne. While Melburnian signs always seem a little more hostile than strictly necessary, that points to the likely existence of opposition. In Brisbane, on the other hand, the most impractical demands are made on the pedestrian without so much as a blink. It doesn’t appear that anybody thinks that being told to KEEP TO THE LEFT and NOT BLOCK THE PATH is slightly too much control for a pedestrian&cycling-only path in a large leisure zone.