Firstly, calm down.
Secondly, as I said, since Rh - is so rare, most Chinese dosen't even know which Rh blood group they were. If the army decided to make Ph blood group information on all dog tag, it would have to test every servecemen and women first, that means money and, most important, time. This also means to change the whole emergency blood transfer system (kinda pointless to have you Rh infomation on dog tag but your feild hospital dose not have the ability to react according to it, right?), from frontline medical handbook to hospital blood bank, which also need money and time.
Also, this is still an alpha test in only 13 units, it's not final.