moffat’s companions’ lives are all so strangely ungrounded in reality and i think it’s a good example of his very weak writing. in day of the doctor we see clara teaching - no explanation, no mention of it in the episode, and no build up to it. although obviously this was a (really lovely actually) nod to canon, it’s not the first time this has happened; amy just “became” a model in one episode and was never shown like this again (after her first job was as a kissogram). it’s impossible to imagine this happening with any of russell t davies’ companions, who all had lives incredibly minutely planned out; rose and mickey found their path to success obstructed by class boundaries and working manually, donna worked a succesion of uninspiring office jobs and even well off martha was shown physically working very hard to achieve her medical degree.
this ability to skip through professions as well as change locations and dump family just grounds the idea that moffat’s companions are strange, non-human, undeveloped creatures. their lives, trials and tribulations don’t matter outside of the doctor, and it’s like they’re a succession of barbie dolls; “i can be a model! i can be a teacher! i can be an archaeologist!” with an awful lot of pluck, a cheeky grin, and no substance whatsoever