An anecdote from today that adds to the discussion.
My dad, who very very rarely goes to the downtown area from his perch in Clay County, was in downtown today to go an event at the downtown library this morning. He parked at the library garage. I asked him about the event and he volunteered the following:
"Gosh, it sure is expensive to go to the library - it cost me $7 just to park!"
Will he ever return to the library? Who knows. But that $7 price will stick in his head, I can tell you that for sure.
It does seem a bit penny-wise, pound-foolish to spend nearly $100M on the library, and then potentially turn people away from visiting because of the high parking charges. $7 does seem pretty high for 121 minutes of parking.
To answer the question: "Why does Republic Parking need to be guaranteed a profit on a brand new garage, when they own many other parking garages downtown?" I think it's as simple as the garage would not have been built without the guarantee.
Did Republic finance and build the garage?
One could certainly make the argument that the city shouldn't be "guaranteeing" profits for any business. On the other hand, I don't know if the city should be in the business of expending precious capital dollars on new parking garages either. If the city believed that a garage was needed there to support City Hall, the Library, MOCA, etc., (let's just assume that premise is true) then it could have paid for one itself (bad idea, I would say), hope that the market steps in and builds one (that could take a while), or provide this guarantee. Seems like the latter choice was the best of admittedly poor options.