I get the impression that Trump is sort of a seat-of-the-pants guy (a kid giving a book report on a book he never read): He has not held any deep policy positions for long because he never thought about them before. When he had to announce a platform he probably spent a few minutes with somebody else's list and just used his gut reaction to proclaim his positions. Then (much) later he actually was given a few relevant facts and possible implications, so he changed some of those positions.
I think we have certainly seen that on immigration. He started out with the simplistic: "Build a 30 foot wall!" But right in one of his "wall" speeches he brought up the possibility of a 31 foot ladder. His current position is tending toward a much more physically possible plan.
All of his flip-flops might be such. "Trust me" might actually mean "I'll think of something".
