While many people enjoy using Unicode symbols in their own code (which has happened because it’s become so easy to type with common tooling!), and you’ll see it in a lot of examples and internal implementations, it’s much less common for it to be required to access any API. I don’t recall any feature of the base language or standard libraries that requires non-ASCII symbols, even if there is a Unicode shortcut.
Is there a particular Unicode-only API you’ve been aggravated by?
(The main external package I know whose API requires a lot of Unicode symbols is the Gridap.jl finite-element library, which is a great package but in a specialized mathematical domain where the symbols make a lot of sense. So, while there are examples of such APIs in the Julia ecosystem, I wouldn’t call it “widespread”. It’s a decision that the developers of each package have to make for themselves.)