Not sure what the purpose of this thread really is. This is a forum where people can come for help when they have knowingly or unknowingly done something wrong. IMHO, there aren't THAT many new threads each day.
The ones I notice are either a passenger mistakingly thinking they can buy on board (as I was scrabbling to get my tickets while the train pulled in this morning, after a long queue I can sympathise), or where the railway industry is defrauding passengers.
Looking at the most recent posts:
Railway at fault (Dumfries - Glasgow mobile ticket dispute
Media Report on Lengthy queues (This mornings Northern Revenue Op - Liverpool Echo)
Hypothetical (Correct process to follow - unable to buy at origin)
Railway at fault (Default Northern Delay Repay Problem)
Railway at fault (Sept. GWR delay-repay claim, first response Dec)
Complex routing minutiae (Complaint To The Department for Transport About Fares Changes Proposed By Great Ang)
It's only after all that that we get to the first first-person report of a passenger in the wrong
Lost Ticket compounding the problem (Paid for a ticket, lost it, then got read my rights. Any advice welcome)
First actual fare avoidance, which they admitted and want to know what happens next (Settlement fine/cost)
As for the assertion
"I'm am genuinely staggered with the number of people that seem to want to avoid their fare"
I'd be more staggered with the railway industry that are constantly making mistakes (more often then passengers based on the last few days in this forum) and getting away with it.
As for the gist of the "I won't pay unless I have to". Unlike a loaf of bread of tank of fuel, travel on a train has no real cost. If a passenger doesn't travel, or if they do but without a ticket, there's no real difference for the railway company. It's more like copyright infringement (say ripping a CD to put on your ipod), or not paying for a tv license, or as the OP mentioned, sneaking into a cinema. There's no specific loss to the company, but if everyone did it the service wouldn't exist.
I suspect that people caught sneaking into the odeon wouldn't be hauled up in court, just thrown out. Copyright infringement, the railway, and the tv license, seems to attract rather harsh penalties considering the loss, compared with say shoplifting.