I was on a 188 last week and between Waterloo and TBR two guys at different stops got on the backdoors ducking down so the driver did not see them-the first time i was no where near the doors but the second time i was and shouted at the guy he was getting on the wrong doors and he was very annoyed with me but realising he had been spotted he got off. The rest of the people on the bus did the very British thing of tutting loudly and saying nothing.
It does make me wonder how much money is being lost overall on evasion if this is anything to go by and how bad are we all for allowing other people to get away with it and saying nothing
I have been told several times by inspectors on a bendy that I should touch in when using a travel card, even though it is not deducting any money. I never do. And this (interesting, but exhausting) Wikipedia page about Oyster appears top confirm it.