Why does everybody use unanchored namespace declarations (i.e. std:: not ::std::)?

Question

It seems to me that using unanchored namespaces is just asking for trouble later when someone puts in a new namespace that happens to have the same name as a root level name

Answer 1

Okay, you say that std is only an example. But to me it appears your question is only applicable to a case where somebody does something as evil as overriding std.

Let me provide another example:

namespace logging
{
    // Logs to local file
}

namespace server
{
    namespace logging
    {
        // Logs to remote destination
    }
}

namespace client
{
    namespace logging
    {
        // Logs to local file and to screen
    }
}

In this case, not prepending :: results in default behavior.