Hard to say if positive outcomes for the average person in Australia started to decline before or after meth increased.

From my anecdotal (but significant observations), there's a coroally with people taking up hard drugs in townships where our youth have no observable pathways to a content adult life. It's my hypothesis people are giving up before they've started.

Regional Victoria and Regional Queensland, it's especially rife.

Edit: not to say other regional townships are worse or better, just haven't spent a significant enough time to observe it.