This concept of "used to" vs "understand" reminds me of an interview with Feynman where IIRC he explains how can magnetism work at a distance to a layman person. He discusses about the "why" questions and how you keep getting deeper and deeper each time you ask "why". He concludes that his explanations won’t be satisfying for the other person, saying "I can’t explain this to you in terms you are more familiar with". I thought it was interesting and related. I’ll try to find that video.