I don't think routes and tracks are supposed to match what a road on a map says, but rather draw on top of them where your route/track goes.
For example, sometimes people will post an actual track of a hike they went on, but the map may be slightly off, so tracks don't follow the map but rather coordinates of where your GPS says you traveled. I would assume that on this website routes also aren't designed to follow a trail or streets, but rather from point to point of where a user told them to go. So if you had manually on your computer created a route (point to point) of where you think you went, others could follow it by having their GPS unit draw a straight line to point 1, then when they get there, point 2, etc. they'll get to the destination eventually, although on their screen it won't be as "snug" as an actual track of where you went.