Python is actually a good example of this. Look at the library ecosystem built up around scientific computing. None of that is in the standard library, yet there is a common set of packages being used.
C++ takes the approach mentioned of having a rich standard library (Boost) that is a separate project from the core language. It (IMO) does not work very well. Many C++ programmers don't use Boost and generic C++ libraries are unable to use Boost as a dependency.
That is because a boost installation litters your hard drive with several hundred thousand tiny files. I can't in good conscience require end-users to install that monster to compile my 10Kloc project.
As a result many libraries are close to de facto standards because any Java dev can easily get those libraries, regardless of being on Win, Mac, random Linux distributions, etc.
Node.js is popular, but it's not 'standard'. It's not part of any ECMAScript standard libraries, which would be the requirement if it was to be standard.
I don't know the situation with Go that well, so if it has a http library in the standard I'll take your word for it, but there do seem to be some popular non-standard http servers like Caddy.
As for Python, this is probably an example of where the impact of standards is not that great. How often is the standard http server used compared to popular third party alternatives? Are there any web apps you know of that are using the standard http server in production?