> It feels like the only way to change a career is 1) get a job doing exactly what you were doing before (e.g. React dev), 2) at that job, do something tangential for a while (e.g. UX design) and then 3) with that experience, go and find a new job in the new field.

I've noticed the same and would also be interested in hearing how she transitioned. It might have to do with how in demand employees are at the time of hiring. In a tighter job market employers are more picky.