Yes, it is the default behavior, because the default locale, as for most (almost all?) programming languages (not just Python), is the C locale, until you change it.  The reason for this is to get consistent behavior no matter what the locale is set to, unless you explicitly enable the local locale (or some other locale) in your program.

Whether it is worth adding a link is a separate question, but we really don't get this question often, unlike some other FAQs.