So yes, for all practical purposes the barrier to genuine understanding of scientific theories and techniques is high enough that a layman cannot hope to have more than a cursory understanding of the field.
First, there is no logical connection between your first paragraph and the second one and I don't see any reason for that "so, yes".
Second, that claim is, ahem, bullshit. I'll agree that someone with low IQ "cannot hope to have more than a cursory understanding", but for such people this statement is true for much more than science. High-IQ laymen are quite capable of understanding the field and, often enough, pointing out new approaches which have not occurred to any established scientists because, after all, that's not how these things are done.
And if we want laymen to trust in a process they cannot understand
No, I don't want laymen to trust in a process they cannot understand.
It's impractical for every single person to understand every single scientific theory. Even the domain of 'settled science' is far larger than anyone could hope to cover in their lifetime.
It's true that scientific authority is no substitute for evidence and experiment, but as Elezier pointed out in one of the streams (I can't find the link right now), it's not like scientific authority is useless for updating beliefs. If you have to make a decision, and are stuck in choosing between the scientific consensus opinion and a random coin toss, the scientific co...
If it's worth saying, but not worth its own post (even in Discussion), then it goes here.