I'm not sure how meeting a few musicians that you may or may not know and playing a few tunes with them in a pub or open space, as most of us do every week, whether at a festival or not, you want to class as "freeloading". And it's not the lack of "anything" thats the problem, its the fact that, more and more, at some festivals the organisers seem to fill every "music friendly" pub with an amplified band, so musicians have nowhere to play (nor indeed is there anywhere to go for punters who want to sit and talk over their beers).
Perhaps you (session man) could say whether you're involved as an individual organising a small festival for the love of it, or work for some commercial outfit doing it for the money. If a festival is organised on a commercial basis I don't see that we owe it anything. If the organisers want to pay us (in free tickets if that's the way it's done) that's another matter, but that's nothing to do with the "folk process".