No need to apologize for the long rant. It offers perspective.
I don't get offended when I'm not taken. There were days on the truck when I didn't want to take an EMT or medic student, so I can relate.
I can also understand some T/O and M/M's hesitation in taking students because if I screw up as a student, they're the ones that get in trouble. Personally, I think that's flawed; if I mess up, it should be me who is held accountable, not my student.
I can say that so far, all of my trainers have been great. Patient with me, letting me do my thing, and offering tips, tricks, and advice how to better my operation, which is always going to have room for improvement. If they ask to take over, I don't get offended. I understand that they have to be on schedule, and if I'm slowing them down significantly, I can't blame them for taking over.
After every trip, I always ask my Trainer how I did, pointers, ways to improve, etc. I also try to ask the Conductor how the ride was, because a. they're in charge of the train, and have the power to pull the cord, and b. I don't want to throw them (or the passengers) around. And I always say thank you.