The speaker only asks four questions in the poem, but they sure do pack a punch.
Line 14: When the speaker wonders if these folks live in the station, she sets herself apart from them. We know from this question that she's an outside observer, looking in at their lives. That tells us that this poem is a whole lot of guess work and not much else.
Lines 28-30: These questions reveal just how in the dark the speaker is about these people's lives. She can't even fathom why in the world they have a doily draped over a table. It's as if she's really asking, "when you live in a grease-caked dump like this, why bother decorating?"