I've explained this earlier too, but consider those parking fees more as road tolls than service fees. Those are in many cases for private roads, owned by a handful of people who pay for maintaining those roads. When all of a sudden in many cases dozens or even hundreds of cars storm in, they leave a mark and in my sense of justice, it should be payed by the spectators (or by the organizers and then eventually by the spectators). So if there wouldn't be a parking fee, it'd be a robbery in my opinion.