If that has been done, then it simplifies the dispute as you can objectively verify whether the complaint matches the official data and Google should not be routing cars there, or if the maps are correct and the appropriate solution would not involve Google - e.g. if a road is physically impassable then complaints to whoever is responsible for maintaining that road; if there are barriers or "do not enter" signs on a legally public road, then complaints to the authorities to remove these barriers and punish whoever put them up, if a path is marked public but you think it shouldn't be then legal action to try and correct it (which may or may not succeed), etc.
Yes, you absolutely could lobby for someone to write a law requiring Google to respond to nuisance requests from their navigation services. That is basically what DMCA does, after all.
Hypothetical example law: OK, you have a good-faith presumption up until someone emails you a copy of a deed and proves it's their driveway, then you legally need to correct it within X days or penalties start to rack up.