A fairly relevant YouTube piece I came across:
Why There's No Turnstile Jumping in Vienna "A short look at Vienna's refreshingly turnstileless public transport"
One question to consider is what we mean by fare evasion: while there are those who did not pay the fare for the journey they intended to make, with the intent to not pay it, which is very definitely fare evasion; there are also those who intend to pay for the journey they intend to make, but, for all sorts of reasons, don't pay for the journey that they do - to what extent is this fare evasion?
I think to cut fare evasion a culture change is required - both with society, that the social inclusion, honesty and good citizenship that include not fare evading and also very much else become the norm; and on the railway, to 'love' its passengers, providing good service in quality and value terms, so that of course they can pay their correct fare without any excuse, so that everybody who needs to know, knows they have, and that when things go wrong, so they don't make their intended journey, its not a problem - so that passengers will 'love' the railway back, and pay their correct fare.