It's hard not to believe Riviera is paying more for the skyliner than CBR/POP/AoA. How would transportation be over double if it was even?
It could be even, according to rooms. It would be odd for Disney accounting to put more costs for the Skyliner on one resort over another, and internal resort "P&L" heads would argue that its unfair for them to get hit more than others. This is the daily life of a P&L in a large corporation.
With that said, I would expect that Poly, VGF, and BLT will blow by the RIV figures once the new monorail goes live. I'm guessing that the large portion of the original cost (which was quite low in today's $) is probably fully depreciated and the charge those hotels are paying (as seen in the current dues) are likely to be just the operating costs and not the depreciation of the acquisition costs. RIV is likely paying the operational costs (which may very well be very close to, or even beneath, the costs Poly, VGF, and BLT are paying to operate the monorail) plus the allocated deprecation of the acquisition and construction cost of building the Skyliner. When combined show the large figure you see.
Personally i'm more than OK for paying a premium for premium resort transportation options.