I think Luna is tuned into the difference between Harry’s epistemology and Hermione’s, and so thinks the question is worth asking in the one case and not the other; alternatively, she is tuned into how they respond to questions of that sort, and Hermione invites them whereas Harry does not.
I think Luna is tuned into the difference between Harry’s epistemology and Hermione’s, and so thinks the question is worth asking in the one case and not the other; alternatively, she is tuned into how they respond to questions of that sort, and Hermione invites them whereas Harry does not.
“Why would I do that?” and “You think like a muggle” sound like she thinks Harry is making an epistemological error.
If she were as tuned in as you say, she should see that Harry asks because he doesn’t see how tuned in Luna is.