The red dashes on the standard OpenStreetMap map represent a path, not a road. No router should direct delivery vans over a path. And no map should display it as if it was a road. So I wonder if the van drivers you refer to are really using OSM data.
OpenStreetMap could likely be improved by tagging the relevant sections as driveway as explained above, and removing the name if it is not right. But as I said, that might not help if the issue is not with OSM data to start with.