Because facebook had years to fine tune this process. I don't think they had one kill-all switch that they pressed one morning after writing the fake name algo. It really helped that facebook grew in a very carefully plan Ed manner. On the otherhand, google plus' growth is kind of random from a geographic point of view. Why is this relevant? A lot of fake name confusion arises from lack of knowledge of names from another region. For facebook, they could soften specific criterias that would typically denote a bad name if the name ends up being a legit one in Thailand and there was a recent spike in Thai signups. G+'s lack of planned growth really hurts them, this being just one instance.