Maybe I should've been more clear about "scope".
Standard libraries can pick their scope of functionalities and depth (or completeness) for each functionality. Nowadays every programming language is expected to come with a good string support, which is about the scope. But there are a lot of string operations you can support. PHP for example has `soundex` and `metaphone` functions for computing a phonetic comparison key. Should other languages support them as well? I don't think so, and that's about the depth or completeness because you can never support 100% of use cases with standard libraries alone. Ideally you want to cover (say) ~90% of use cases with a minimal number of routines.
Leftpad was clearly due to the lack of depth in JavaScript and Node.js standard libraries. JavaScript now has `String.prototype.padStart`, and an apparent name difference suggests a good reason that some standard library may want to avoid it: internationalization is complex. A common use case is to make it aligned by padding space characters, but that obviously breaks for many non-Latin scripts [1]. And yet many people tried to use it, so `left-pad` was born with a suboptimal interface, and we know the rest.
HTTP support is different. I totally agree that HTTP is something you want to support in a sorta native fashion, but a standard library is not the only way to do that. In fact it is not a good place to do that because it is generally slower to change (Go is a notable exception but only because its core team is very well funded and strongly minded). Python did support HTTP in its standard library for a long time, but it doesn't support HTTP/2 or HTTP/3 at all and Requests or urllib3 are now the de facto standard in Python HTTP handling. Modern languages try to balance this issue by having a non-standard but directly curated set of libraries. Rust `regex` is a good example, which may be surprising given than even C++ has a native regex support. But by not being a part of the standard library, `regex` was able to move much faster and leverage a vast array of other Rust libraries, and it is now one of the best `regex` libraries throughout all languages. That's what nindalf wanted to say by different "ways".
[1] For example, `"한글".padStart(5)` will give you `" 한글"` but its visual width is larger than 5 "normal" characters. This is not merely a matter of fonts and Unicode has a dedicated database for the character width ("East Asian Width"). Some characters are still ambiguous even in this situation (e.g. ↑), and the correct answer with respect to internationalization would be: don't, use a markup language or (for terminals) a cursor movement instead.