I very much doubt if they are taking turns to win. It is hard enough to get horses in the right condition and pick the right class to win. If you are suggesting that races are 'fixed' by trainers, I find it implausible for a number of reasons.
The only thing that is 'fixed' are the odds aimed to fix 'illegal bookies' for good.
Did you notice the familiar race winners each time? Powell,Cahill,Saimee,Beaseley..........
What the fark happened to the locals? If they are that bad, why issue them a license in the first place? The apprentice jockeys in HK are doing alot better than those in Singapore and it wouldn't surprise me if they beat most of the seniors with their arms tied to their backs.