Many parcel maps were created without the use of aerial ortho photography, if they used photos they were distorted and then they tried to get a best fit. Some were created by reading deeds or survey plans and then this was pieced together, if they were recent they used ortho photography.
The roads are really right of ways(ROW) on tax maps, i.e. may be 50 foot wide and the actual road is 33, usually they were drawn 1/4 inch wide on 100, 200, and 400 foot scale tax maps. So unless they used planimetrics for an edge of pavement they rarely match to the actual road. If the tax map shows a boundary line 100' from the ROW, and you use 100' from the road, you end up placing the parcel in the wrong location.
The cul-de-sac was probably placed by an autoCAD site plan before it was built as they need lots to sell. The end product was the homes showing the misplacement of the CAD drawing, and it was never adjusted. Basically you see a compilation of different materials at different scales with their own errors knitted together by someone using some knowledge and luck. Thus the reason most Tax maps have disclaimers saying for inventory purposes, as this protects the municipality from legal issues as most boundary disputes need to be settled in court.
A side note, some deeds say they own to the middle of the road, these are never drawn on a tax map this way.