I guess it's about trust. If a kitten is exposed and handled by human beings at a young age, it learns that this will not endanger it. If they don't get that exposure, they don't trust humans. This is true even if you feed the cat regularly as it grows. The crucial window of socialisation has gone.
But there are degrees of feral-ness. I can get within a metre of Jessica if I am putting down some food and she is standing by ready to eat it. Others such as Ron (eating with Jessica and Bette Davis below) and this other ginger peeking out from behind the wooden chest (also below), are extremely guarded and will bolt if you come within 4 or 5 metres of them.
The boys seem to be more feral than the girls. This is curious. The boys probably have a wider roaming range and therefore form less of an attachment to their village than the girls. Perhaps that's it; or maybe the boys have more to fear from humans. I suspect the odd aggressive male has been chased off by the odd human now and then. Certainly our neighbours do comment on how 'very, very bad' (malisimo) certain large males are when they bully everyone else.
Maybe the males have to be more guarded, generally. They have to watch their backs, that's for sure. They have a clear pecking order and if they do happen to be the alpha male (NoNeck probably at present - here he is, peering at me from behind the rock) there will be regular challenges; and if they are somewhere else in the pecking order, they are under threat from above and below, unless they are on the very bottom of that league table. Hard to get a good night's sleep either way! And best to keep one eye open, and one’s back against the wall. Perhaps you end up being guarded and suspicious about felines and humans alike.
Of course the same dynamic can be unhelpful. If I want to trap a male to get him neutered, you can bet it will be the more relaxed (and already neutered) females who will explore - and hoover up - the tempting treats on offer, nonchalantly skipping in and out of the as yet unset trap. It may indeed seem like a game in which the human puts the delicious morsels carefully in the trap, Bette Davis or Jessica gobble them up as soon as back is turned, at which point the human shoos them away to put more delicious morsels in! What fun.
Short memory, given they have experienced that trap as the beginning of the TNR process. But I guess it's an affirmation of the fact that they don't think anything really terrible happened to them in that process!