I'm not sure I agree with your points here and I really hope I'm understanding wrong here, indeed I hope you are NOT a a train driver instructor otherwise you are missing some essential elements of the recruitment process!!
These test are not designed to determine a natural ability to pass them!! Nobody has or had a "natural" ability! We all learn!! If you pass these test is because have learnt through life channels such work experience, job experience, hobbies and so on "abilities"! You haven't been made by the "factory" with certain abilities you simply have learnt abilities! There is no need to know what is the real meaning of a fuel gauge or similar, the job require you CHECK that gauge is working within a certain range. These test are designed to help the TOC to identify who can learn quick and adequately a lot of informations NOT who has "natural" ability! You might have brown or black hair, or eyes, that's is natural!!