Swift (used for Apple devices) has them (see the Integers section):

https://docs.swift.org/swift-book/documentation/the-swift-programming-language/thebasics/

So it was actually written in a language that has them...

C# has them (goes without saying)

Java doesn't seem to.

This is still clearly far from "virtually all."

Why use a signed integer for something strictly non-negative (ignoring bugs ofc)?