GPS is capable of that if used properly and there is no interference from trees or buildings.
I measured a cinder trail that is primarily under trees. When I put the track into GoogleEarth, the track varied left-to-right by over 50 feet. When I measure a 1-mile downtown street, the track shows me going into buildings on either side of the street. This is also not accurate.
Just want to reiterate that GPS devices must have a clear view of the sky, and free of signal-diverting obstructions to the side of the route.