There are two aspects I see. One, Google may be enforcing more aggressively and less consistently. Two, the differing initial demographics. Facebook initiall

There are two aspects I see. One, Google may be enforcing more aggressively and less consistently. Two, the differing initial demographics. Facebook initially launched to college students and they established its initial environment. G+ started with the technorati, many of whom care deeply about this. Some of whom have handles going back longer than Google has existed.