First, you're looking at two separate things. Hotel revenue management systems don't take third parties practices into account when setting rates. How Citi handles their reservations is largely irrelevant.

Second, hotel revenue management systems are wildly complex. One of my past jobs was as a hotel Revenue Manager. In most cases, the computer really is smarter than a human. Hiccups occur when unexpected events happen. Things like: sudden weather events, terrorism/coups/military actions, one-off events like political rallies, and lose-and-you're-out sporting events (like NCAA Final Four). Managing those things are why Revenue Managers haven't been completely eliminated.

Based on the (non-Citi) rates presented, there's nothing odd happening. A $4 difference over 5 days is nothing for a 1,467-room hotel like the Tropicana. So, those rates are basically equivalent.

As to why the difference in daily rates, my best guess would be that it relates to likelihood that the reservation will be used in full (without an early departure or cancelation). The system will look at how likely someone who books a CA Resident rate approximately 45 days in advance using the website (versus a corporate or online travel agency) will actually stay. It will also look determine the likelihood that the room can be resold and at what rate if it is canceled. Each of those calculations are used to determine the daily rates offered.