My understanding is there are fewer full service outfits in the state right now than there are outfitter permits so its basically a guarantee that they will get one each year. To qualify they must offer lodging and meals with appropriate food service permits.
I've seen some outfitters sell to the highest bidder and others offer a limited lottery for the chance to win "their" permit. I don't disagree that its outfitter welfare and it definitely hurts my odds as a nonresident when trying to draw a tag. On the other hand I don't see many wealthy outfitters and I'd like outfits as a whole in Maine to not go extinct.