If hoping to get away with it is not intent to defraud, can you explain what it is?
Intent requires actively doing something (e.g. hiding in the toilet, pretending to be asleep) to avoid paying. Many people, rightly or wrongly, feel that if the guard doesn't get down the train then that's the railway's problem and not theirs.
I can see both sides of the argument.
Most people I see "hoping to get away with it" have boarded from stations with a full range of ticketing facilities, or a major London terminus.
Not every ticketing offence happens between Reading and Paddington though.
I've committed a criminal offence if I get on one of your First Great Western trains without a ticket. Five miles up the road I can get on a First Hull Trains train and buy whatever I want from the guard, without a penalty. If you can explain how this is consistent, I'd be very grateful.
Ticketing practices are very lax in many parts of the country, and people get confused by it. I've said before, I thought it was ok to buy on board until I started posting here. I'll give a few examples:
TPE's automatic announcements say "if you choose to walk past an open ticket office, you will only be sold full price tickets on board". That implies that I
can get on board without buying a ticket, but that it'll cost me more money, a simple cost/benefit exercise. In reality I am committing a criminal offence. TPE don't tell me this.
I travel to work from Apsley every morning. The guard is selling tickets throughout the journey- "does anyone need a ticket?"- and there is an excess fares window at Euston. For over a week now the station ticket office has been closed, apparently due to staff sickness according to London Midland's twitter, with only a solitary card-only TVM available. Taking the ticket office away due to staff cuts (if there is no spare staff then LM are understaffed) only emphasises this point. These things imply that buying on board is an option, when in reality it is not.
In Yorkshire, most ticket offices were closed during the 1980s, with everyone having to buy tickets on board the train. People get used to this, and expect that this is how things are done, just like on the bus. Guards are usually happy to sell tickets, and appreciate the commission, again implying that buying on board is acceptable.
And I've already mentioned the Open Access operators- your employer owns one of them- who make an advertising feature of buying on board.
The current situation is farcical, and I think it boils down to penny-pinching from TOCs and then profiteering from the confusion. Northern are particularly guilty of it, using the PayTrain idea to cut ticket office hours (outside of PTE areas) and then using fear to profiteer from the confusion.
I can't think of another industry where they would try and prosecute you for paying at the wrong till.