[takeda]

It's simple. Python was created before HTTP even existed. Since then a lot of things had changed, and once you create an API, it is hard to rewrite it when new use patterns emerge.

It's easier for a 3rd party package to come up with a better api, because they can start brand new. Also when there's a radical change it is easier for a new 3rd package to take over. Httpx is example of such evolution, although not due to changes in http but this time changes in Python, it makes use of new functionality that's harder to implement in requests, mainly adding async support and type annotations.

[viraptor]

Python was created before json existed, and yet: https://docs.python.org/3/library/json.html

It's not a hard rule, sometimes things do end up in the standard library.

[takeda]

Of course it could be added later (there's urllib that almost no one uses), I meant that Python is older than HTTP and HTTP evolved a lot during that time.

Once you create an API, it's hard to change it. HTTP initially was very simple and evolved over time. Things like REST, JSON encoded messages, cookies, authentication (albeit rarely used), keep-alive were added incrementally. Today's HTTP is used completely different than 30 years ago. Python already had urllib, then urllib2 which was renamed back to urllib in Python 3, but its API is still behind how HTTP is used right now.