My hunch is that they are just using an existing framework that does that, and it may require some digging into the configuration to disable that (or worse, have to change some code). Since this is never going to be an urgent thing it will never be fixed.

I work in MacOS VSCode frequently, and whenever I open a large repo with a huge number of files, it's PIA to find the scrollbar. I have to hover the mouse above it to make it appear, but how can I hover above it without knowing where it is?

BTW if you share the same frustration with VSCode, please vote this ticket: https://github.com/microsoft/vscode/issues/244123