He is amazed that people who don't use a skill forget how to use it? You don't trim an airbus and a lot of carriers forbid use of manual thrust. Five years of doing that and you soon get used to that and that alone unless you can afford to keep a single engine rating up. It's not amazing, it's expected. However, a couple of hours in a fixed based 737 sim and most people would regain the skill fairly quickly, in preparation for the big even,t £300 for a future career is not a lot.