Improbable Age: Happens both ways, in the Empire. On the one hand, you sometimes get improbably young people doing various jobs, partly because of those very population dynamics we mentioned back under Immortal Procreation Clause making it very useful to get new brains into the useful-production fields as soon as they were competent to do so (and, note, the Imperial concept of “majority” is based entirely on demonstrated competence, not age, so prodigies really can leap ahead); usually in ‘prentice-level positions along with continued education (because those same demographic factors and the production models they favor make grunt labor very much less than useful), and quite possibly still with limitations on their tort-insurance-covered-rights-of-contract, it is true, but nonetheless, out there doing stuff.
Happens at the other end, too, though – given the social requirements of mobility and the personal requirements to keep fresh, there is a longstanding tradition of recurving; namely, for people who’ve stayed for a long time in a single career to retire, take a sabbatical, and then start afresh in some different field (often a very different field) that might interest them. So finding old and highly experienced people doing relatively low-level jobs way outside their field is also hardly unusual, although the generalizable part of their experience does mean they tend to advance relatively fast. (Also, the benefits of intentional or serendipitous cross-pollination between different fields don’t hurt, either.)
And, of course, the immortals do tend to look quite young… so long as you don’t look them in the eyes. Or watch them in action.