I am only speaking here for the maker-traders who struggle to make a living from their craft, and judging from the other postings I am the meanest of them all.

To sum up the waffle to follow below:
Free pitches for traders: Yes please, so that we can make a living.
Free tickets for traders: What on earth for, we are there to work!

Free pitches will encourage traders to attend an event.
Free tickets will encourage traders to bring all their mates and have a free party and neglect their stall.

I make historical shoes and sell them on my stall at historical events. I have never considered pitching at a Folk festival as my stuff is too specialized to sell to anyone except reenactors. This is a good thing too and I am not going to change it.
When I work I work - at historical events.
When I play I play - at folk festivals.

What I find lacking in this thread is the distinction between work and play and the fact that the festival organizers can expect a professional attitude from traders.

For example on my own trading circuit English Heritage give me a traders pass to access the site and do my job which is stall-holding. It is business. I am expected to be professional about it which means that during business hours I work, not just close shop for a while because I want to see the joust or fancy a break at the burger van or am too hung over to open the stall on time in the morning.

Traders who trade for a living:
Need to make a reasonable profit to make it worth their while.
A reasonable profit should be at least minimum wage once you counted all the hours you are working at an event, from start to finish, which is usually from Friday 6am till Monday 10pm. That is often some 60 hours, and that is when you are not trying to hold down your stall in a storm or salvage stock from a flood. Plus the hours it takes you making the product you sell, plus petrol, plus public liability insurance, plus the cost of the materials for your product and other expenses.
You need to shift a lot of stock to end up with £5.00 an hour if you add it all up. I never make minimum wage at a festival once I have done the maths.
So a free pitch is one thing that would help with actually going home with some money in your pocket.

Okay, if you feel generous, give them free tickets for the evening events, and no more than two. Hardly any stall (except catering) I have seen at folk festivals needs more than two staff.

Non-professional traders:
Who are doing it for charity, for fun, as a hobby, who are running the kind of stall that a living cannot be made from, are obviously in a different category. However this kind of trader is usually on good personal terms with the festival organizers. I think nobody would object if they brought a few extra staff to work only part-time (part time as in 50% not 5%) on their stalls and be classified as stewards rather than proper traders.
However, the customers cannot tell the difference and I think that not-for-profit stalls should present themselves to the customers just as professionally as the full-time traders.

As to free tickets for performers:
For the day? For the evening? For the entire event?
Whatever is appropriate, but there should be a balance between what they are giving to the festival and what they are receiving.

Free tickets to performers friends:
Unless the performer is a megastar and needs placating, why at all? And even then would it not be fairer to pay the performer a higher fee and then let them buy tickets for their mates from their enhanced wages?
Because what exactly is the free ticketed performers mate contributing to the event?

Cheers,
Ana