Roxanne sees Jack as an oddity; cops aren't exactly know for their competence in Metro City so seeing one who is basically a superhero with a badge is new and unusual. She's probably going to nosy around him some more, which -- is probably the exact opposite of what he wants. But it's out of respect and interest, really. Really.

Garrus really admires Jack. He's not quite to the mancrush on Jack Bauer level of interest, but he'd probably follow him to hell and back with no more than a rifle and his bad ass attitude. In short, he's Shepard, Mark 2.