I really didn't think there was that much variety in LEO due to the cost of launching in a retrograde orbit. I thought it'd be mainly prograde plus some normal velocity due to inclination.
Retrograde orbits are uncommon as far as I know, but polar orbits are common for earth observation. A satellite going south could meet one going north.
Also unless you launch from the equator inclined orbits are cheaper to reach than equatorial. The ISS for example goes just far enough north to pass the Baikonur Cosmodrome.
The inclination matters, though. If something heading north at 41 degrees inclination meets something coming south at 41 degrees inclination, it's a serious collision.
(And, of course, every satellite has to spend half its orbit going north and half going south)
