Sight lines, rights of way, restrictive covenants and the need for new entrances are buyer beware territory.
To get planning permission, i.e. approval from the authorities to build a new house, you must have adequate road entrance sight lines. A rule of thumb is that the higher the speed limit on the road, the further away you will need to be able to see traffic coming from both sides (sight lines), which may make a site impossible to build on if it is on a winding road with a high speed limit. Check the planning regulations in your area.