I've had a friend banned from facebook for using a nickname, instead of a real name. Facebook may not do it as often, or it may not be as publicized, but they do also have a real name policy in place.
There's a lot more to it than that. Part of it is that Facebook does have a "real names" policy, but they don't actually define what a "real name" is, and they also don't enforce it nearly as recklessly as Google does.
Also, it's important to separate the notion of a "real name" from a legal (wallet) name. A legal name shows up on government issued ID, and is called "legal" because it falls within the law of that government.
A "real" name, to me, is a label that can refer to an individual, animal, place, or thing within a given context. For example, I consider "aestetix" just as real as any other name, and there are some people who have known me for over a decade, solely by "aestetix." To them, it's quite a real name.
But consider people who use different names for political reasons, social reasons, safety reasons, etc. Mark Twain, Voltaire, Richard Bachman (aka Stephen King), and so on all had very legitimate reasons for using a non legal name. Imagine you're trying to post updates on Facebook about awful things your oppressive country is doing to you (think Iran or Syria). Or imagine that you have a stalker who is trying to hunt you down. The list goes on.
I think it's pretty obvious that none of the major websites have thought this stuff out very well.
I think Facebook has thought this stuff out quite well: When people use real names on their service, it's easier for family, friends, and college acquaintances from thirty years ago to find them, thus increasing user engagement with the site. It also gives them an easy excuse to delete troll accounts. Furthermore, having people's real names (and often address etc.) makes them a more attractive target for advertisers. Most of the Facebook biographers seem to agree that the real-name policy was one of the factors that helped it win out over MySpace and other social networks. (Among many, many others, of course.)
In light of how much money this policy is presumably making them, and considering that they have about a billion customers who seem to accept the policy as is, I strongly suspect they don't care in the least that the occasional person with an unusual name falls through the cracks, or that they're screwing over people who need to remain anonymous for legitimate safety reasons.
Do I agree with their decision? Not at all. But I think they know exactly what they're doing.
I disagree with this assessment. People on Facebook tend to use the name by which they'll be most recognized. If your legal name is William Jones but most people know you as Bill Jones, you'll probably be on Facebook as Bill Jones. I don't think there's evidence Facebook has thought it out well, they simply haven't been nearly as idiot in enforcing it.
One point I want to clarify: I do think Facebook knows what they are doing in collecting marketing data, in the same way Bank of America knows what they are doing in holding bank accounts. What they are not doing well is creating an accurate representation of identity online. If you follow Chris Pool's thesis ("Identity is prismatic"), then nobody is doing this well right now.
On the plus side for Facebook, they only care if you get reported by another user. They don't seem to be running any sort of automated "fake name" detector.
On the minus side, some people on Facebook use reporting as a form of trolling, and it appears to be fairly easy to get people kicked off of Facebook with enough flagging persistence. For friends of mine who run a religious ministry, basically everything they post gets flagged, and they regularly get kicked off the site for a few days at a time. They've finally gotten it under control after several long phone conversations with FB support.
Also, it's important to separate the notion of a "real name" from a legal (wallet) name. A legal name shows up on government issued ID, and is called "legal" because it falls within the law of that government.
A "real" name, to me, is a label that can refer to an individual, animal, place, or thing within a given context. For example, I consider "aestetix" just as real as any other name, and there are some people who have known me for over a decade, solely by "aestetix." To them, it's quite a real name.
But consider people who use different names for political reasons, social reasons, safety reasons, etc. Mark Twain, Voltaire, Richard Bachman (aka Stephen King), and so on all had very legitimate reasons for using a non legal name. Imagine you're trying to post updates on Facebook about awful things your oppressive country is doing to you (think Iran or Syria). Or imagine that you have a stalker who is trying to hunt you down. The list goes on.
I think it's pretty obvious that none of the major websites have thought this stuff out very well.