Have you tried writing a PS1 which shows all the info that's demonstrated on the linked page?
I have. It's a decent chunk of work. It's a whole lot more work to do it well. Did you remember to handle the situation where the git repo is so gigantic that running `git status` takes half a minute? Or the case where there is a .git folder somewhere but permissions are wrong or it crosses a mount barrier so `git status` prints a page of text to stderr? Does the way you're finding the current branch handle the case where HEAD doesn't point to a branch?
The only way your prompt "already does" this stuff is if you've spent a whole lot of time configuring it and tuning it, or if you're already using something like oh-my-zsh. And if you're already using something like oh-my-zsh, well, starship is just a competitor to (the prompt portion of) that.
