The Aikikai Hombu regulations are reasonably strict as regards eligibility for Fukushidoin and Shidoin but leaves the actual appointment process to individual organisations.
I was appointed Fukushidoin & Shidoin by Chiba Sensei during his time in the UK without any examination, but he now has a strict examination procedure.
We also have a fairly strict procedure but based on continual assessment over two or three years with special training sessions etc.
As for someone starting Aikido with the ambition of being a teacher; why not? Providing they are prepared to work at it over a long period they should acheive their goal.