Human rogues can't sneak attack while hiding in shadows?

[Norfleet]

Medieval buildings may be shorter, but the streets are also narrower - especially in alleys where you're not expected to be able to drive an oxcart through it. Plus it was common practice to make the upper stories overhang, to get more living space - so the upper stories above that back alley may be only 2-3 feet apart.

Point. In places where the alleys are built in such a manner, visibility could become severely impeded, depending on the angle to the sky.

Having done a fair bit of wilderness camping, no, you can't see the friggen tree well enough to carve your initials on it. Unless you've got a full moon, the trees around you are pretty much a solid black mass, especially in a conifer forest. (In a fir or spruce forest, especially, the canopy is thick enough that even at high noon you have "shadowy illumination" at best.)

My guess is that you haven't been gifted with very good night-vision, then. I've done a fair bit of nocturnal wandering myself, being a primarily nocturnal person, and I've never had a problem with it. Then again, being a night person probably has given me better-than-average night vision. I hate daylight. It burns.