I thought that cost was largely due to the land rights, building of all the stations (including footing some of the cost of attaching it to some of the hotels), and the tech for the POS.
Universal's should be cheaper because it's probably going to go through the center of U Blvd and will only have two (three if it includes WnW) stations in which all the property belongs to them. There will be no POS equipment involved because it all belongs to them.
IMO, Universal has no choice but to connect both properties with their own private transport beside a bus. The traffic will be a nightmare for one. The other thing is that they don't want tourists traveling themselves because there are WAY to many things between here and there that would pull them other directions. I.e Orlando I, skyplex, the new tall spinner they just approved, other eating options, other shopping options, Ripleys, Wonderworks, Titanic, mini golf, go carts, CSI, indoor skydiving, ISquare hotel, etc. One step away from Universal's system will put them to close to escape to the other tourist traps.
When they do build their own transport, they'd be silly to leave the windows open. It defeats the purpose of containing your guest because they will be able to see other options. Cover the screens with HE windows and you can have that 2 minute ride full of advertisements for the next destination. Heck that's what the Vegas Monorail does. "Your next stop is the MGM Grand Station. Be dazzled with illusions from David Copperfield..."
Resorts want you to park your car and only depend on them for the rest.