Kim, I agree with you whole heartedly, the stated price should be what you pay, period !
Unfortunately the world of computers & promoters is full of catch 22's. A few years ago our small arts theater got a grant and bought a ticketing system. We hoped to be the major ticket outlet for our region and generate some much needed revenue.
One of the first problems we had was whether to include in the ticket price the service charges for maintenance, upgrading, and further training on the system.(about $5,000 a quarter)
As I remember, the main problem was that the computer's internal accounting program would have trouble splitting out those service charges from the promoters "take" in a timely fashion, and that with a variety of different promoters wanting us to sell their tickets and turn over their money pronto, it would be too complex to mingle that money.
So, against our better judgement, we had to do just what you're complaining about. And boy, were people unhappy. But, once you've let the bear into the tent, there's no easy way of getting him out.
That ticketing problem, along with some of our boxoffice people who were not people friendly, was one of several causes attributed to our meltdown -- suspending operations for six months and throwing a staff of six out of work !
We started back up last fall, but we don't do big time tickets anymore. That is one dog-eat-dog world !