Following your line of thought; Arpichaya Yubol, the 16 years old who won 5 consecutive Thai LPGA events should be player of the year of the whole world,
It's tough to compare apples and oranges.
Firstly, she's Thai, so she won't get a SeoulSisters award even if she won everything in sight.
Secondly, I do weight the tours somewhat. Success on the LPGA is more impressive than success on the KLPGA, and the KLPGA > JLPGA, etc. So Jin Young Ko and Hye Jin Choi, to me, were fairly close in the Rookie battle, even though Choi beat Ko in pretty much every category. In the end, I felt like Hye Jin's success was greater than Jin Young's even given the greater challenge Ko faced of coming to America and fighting tougher competition.
If Yealimi Noh had won a few more big amateur tournaments, I might have considered her for POY, too.