I also watched quite a bit of the tournament in Spain yesterday. The coverage there was well spread. Whether they were Sky cameras or Spanish cameras I don't know but it was very fair. The winner, James Morrison, was quite superb, and we got to see quite a bit of the chasing pack although none really threatened. (Just checked and Peter Uhlein in 69th was the top American). If only Francesco Molinari could putt. What a player he would be but yesterday was as painful as watching Sergio at times. Reliable off the tee, great irons, missed putt. Over and over again.
The difficulty in last nights coverage is that it was a procession and so there was little else to show. We got a lot of Mickelson and Rodgers, oh the agony of the 17th, but precious little else. As has been mentioned the leader board was US dominated so whoever covered the event it would have been an American fest.
Taking the feed from the host broadcaster is common and is done either by choice, cost, or because the host broadcaster owns the rights. Sky have to take what they are given. The alternative is no golf at all.
I think there is a company called European Tour Productions who basically have a crew that go from event to event and set up the camera, editing suite and feed the pictures back to Sky. Even on the European tour they are taking the pictures they are given