The Civic is misaligned. The Fit is either misaligned or you're taking the corners too fast. Have the tires remounted inside-out on both cars if their alignment is perfect, then you'll wear the other edges...
the civic is really low on stiff springs and i refuse to get a camber kit. i dont feel comfortable taking turns as quickly as i do at an auto-x on public roads. the fit on the other hand is completely stock and the outside wears when i drive it, not when the wife does. go figure.
the wear on the fit isnt really noticeable until you actually measure it. on the civic you can kinda tell when you take the wheel off and look close. but if i just turn the wheel to look at the tread you cant tell. to be honest i hate the civics 17in wheels and el cheapo tires. they are loud and dont have sufficient dry grip for when i really want to have fun.
don't waste your time or time will waste you