The advice has also been that if you are less than 2m from somebody for only a very short time, a few minutes or less, then the chance of catching anything from that person is minute, unless they actually cough in your face.
I didn't do ticket checks to start with then I got bored and also got fed up with just carrying scrotes around for free.
I have been doing some checks (card only, no cash) in the past fortnight and have concluded that about 65% of all the people travelling are scrotes, scratters, druggies and assorted other ne'er-do-wells. Most of them have no ticket and no money.
Of all passengers, with a very very few exceptions, the only people with tickets are those who have season tickets, in many cases from before the lockdown started or those coming back from an airport. Nobody else has a ticket at all even the genuine commuters who have worked out that there are no on train checks and most barriers are open or you just demand to be let in or out without paying because the staff manning the barriers are not challenging anyone. You normally see them hurriedly buying a ticket on their phone when you approach.