I believe one reason, primary or not, is supply and demand--therefore the parks departments realize this and yes, as you stated, a way for them to increase their income...however when spending that kind of money, I would rather have too much time than not enough...

I went with Chifuti this year in Zim---they were running 90% plus on lion for something like the last 3 or 4 years...they did not have a 21 day minimum at that time..however I did hear the price went up substantially since when I had booked it in 2006..

Ripp