I think you have a very narrow view of software development practices. In most companies I've worked at, most tickets are created by the QA team, few of whom have ever seen the source code and there's no reason why they'd ever need to.

They raise a ticket about the problem they encounter, and then other people triage it and try to find a way to reliably repro the issue, and then it gets passed to the development team when there's something actionable.