It's another thing entirely to face an orchestra and listen attentively for 90 minutes or more. I can't honestly say that I usually enjoy the classical concert experience as fully as a movie or highly engaging (lots of patter) pops concert.I think the real problem is that many people have the wrong expectations of how much they should absorb and understand in a single hearing of art music. Just as a great piece of literature demands multiple readings to understand all of the layers of meaning and reference; or a great painting demands multiple viewings to catch the subtleties of dimension, color, and brush stroke; many pieces of art music demand multiple listenings to perceive all of the formal relationships, topical signifiers, orchestrational colors, text painting, et al. These sources of overwhelming information reward repeated listenings, making every listening exciting. But people used to more one-dimensional art can be turned off, because they are used to comprehending everything about the art in one experience. Feelings of inadequacy and frustration, or judgments of emotionless and irrelevant content are understandably common when listening from this perspective. A simple solution to this problem is to encourage your friend to listen to a recording of the music before taking them to the concert. Talk to them about multiple listenings, and ask what was different about this performance, both because of the live environment and because of the newer expectations from the previous listening.
"If it feels like work for me, how can it be that enticing (i.e., generate repeat attendances) for most newbies?"
Along with the problem of single vs. multiple hearings, classical newbies also face the problem of "it's a masterpiece, but I don't like it." But I'll write about that later.