Language choice is orthogonal to distribution strategy. You can make single-file builds of JavaScript (or Python or anything) programs! It's just a matter of packaging, and there are packaging solutions for both Bun and Node. Don't blame the technology for people choosing not to use it.
Why would you want a single-file build anyway, to make it easier to move around on disk? There are reasons for the dep filetree.
Btw, the largest deps in this are React and Open Telemetry.