Virtually all car navigation software, or phone GPS apps in driving mode, will "snap" to a nearby road if the GPS indicates that you are traveling parallel to one. This compensates for minor GPS reception errors.
This can occasionally, in rare situations, be a problem, if you have frontage roads very close to a highway, they can sometimes get confused about which road you are actually on.
It's incessant for me; a significant part of one of my frequent routes is on the service-drive that parallels a major freeway, after taking an exit, but prior to diverging. Depending on traffic, though, it may also be advantageous to stay on the freeway, so both are valid parts of the route.
If Waze instructs me to take the exit, then it assumes I'm on the service drive, even if GPS says I'm still on the freeway. And vice-versa, more problematically -- if I impulsively take the exit, it assumes I'm still on the freeway even if GPS clearly shows I'm on the service drive.
(I can confirm this by running a spare laptop with a USB GPS as a logger, while my iPhone runs Waze. Overlay the GPX on a map later and it's super obvious whether I took the exit or not, but either the Apple location provider or Waze staunchly ignores reality in favor of obsessive road snapping.)
Where this gets stupid is, if there's a traffic jam on the freeway and I dip onto the exit to avoid it, now Waze sees me flowing freely down the service drive, assumes that it's the freeway that's flowing freely, and disbelieves other users who report traffic there. Even as the service drive curves and diverges and I follow the curve, it doesn't retroactively say "Oh jeez, he must be on the service drive after all, adjust the previous data to apply to the service drive and not to the freeway!". So the bad data continues to corrupt the traffic picture and encourage other users to get stuck in traffic they can't report.
I love when I've been traveling at highway speed down a highway for over an hour, and suddenly my GPS starts giving me directions back to the highway from some nearby parallel road when I haven't so much as passed an exit.
In car navigation software it's not all that rare. Chances are the maps are out of date, perhaps by quite a few years (because manufacturers ask for absurd prices on map updates) and you're traveling on a road which doesn't yet exist on the map ...
This can occasionally, in rare situations, be a problem, if you have frontage roads very close to a highway, they can sometimes get confused about which road you are actually on.