I'm not super well versed in this domain, but I believe Postgres columns need to be wrapped in double quotes to respect case, or else they're all treated as lower, or something along those lines?
That's largely only true for schema names and table names, not all identifiers.
The original root cause was having schemas backed by directories, and table definitions backed by .frm files. So on a case-insensitive filesystem like on Windows or MacOS, MySQL enables corresponding case-insensitivity logic for the affected types of identifiers.
