I was interested in this report ( http://www.theage.com.au/it-pro/government-it/myki-bill-mounts-as-fare-evasion-adds-350m-to-tally-20120829-24zuf.html) that states (in the final paragraph) that, of all fare evasion in Melbourne, 72% of the revenue loss occurs on the trams. Just how this figure is calculated completely baffles me, but it does ring true. I don't use the trams as much as the trains, but it never ceases to amaze me, when I do use them, that many passengers appear not to validate a ticket. I suppose some of them have 2-hour or daily Metcards, or a Myki pass (for a particular period) loaded on to their Myki, so in each case they're not avoiding a fare (although my understanding is that they're still supposed to re-validate the Metcard or touch-on the Myki, as appropriate).
It does seem that our society has become much more risk-averse, and so we have "Authorised Officers" in teams (that sometimes seem to include up to 5 people) who are not nearly as nimble as inspectors in days gone by or for that matter as in other cities.