The problem here isn't so much that it's not in the standard library (not everything needs to be in the standard library), but that everyone is rolling their own instead of using third party libraries.
"Everybody" is the problem, there are two proper use cases for a standard library†
1. Vocabulary. Things Everybody will want to talk about. It's easier to communicate if we all agree this is a List<Goose> than if we first have to negotiate do we mean MyLinkedList or ArrayList or HybridStorage::List, and if we can't agree do we need an adaptor layer. Vocab is a reason the stdlib should provide a string type (if the language itself does not), a growable array, a hash table, etc. With generic programming you likely want some algorithms in here too, all & any, sum, that sort of thing.
2. Shared features Everybody will find they need and might otherwise screw up. Trimming trailing whitespace, turning numbers into strings and vice versa, sorting, basic arithmetic, familiar constants.
This should be in category (2). "Everybody" will need this once in a while.
† In C++ instead the standard library functions as a way to not bother with package management, this does have amusing effects like how FreeBSD will end up with a linear algebra library required to build the OS.
I do mostly like C++, yet the linear algebra library belongs on the same garbage box the anti-GUI folks have placed the graphics proposal on, even more so as it depends on something else, most likely not written in C++.
To add pain to the injure, imagine FreeBSD also needing a Fortran compiler to build the OS.
This is something for vcpkg and conan, not the standard library.
Yes. How much you'll want to stick in the standard library and how much into other 3rd party libraries also depends on how easy it is to work with these 3rd party library.
Two examples:
Rust 3rd party library support is so strong, that its standard library itself is actually partially built on top of 3rd party libraries.
Python, especially in the bad old days eg 20 years, didn't have much support for (sane) package management and dependency management, so it was really convenient to have a standard library with 'batteries included'.
Thing is, while C and C++ might be a late comers to the whole cross platform package management, vcpkg and conan are already quite established, what we are having is folks stuck in the old ways.