Comment by dagw

As someone who has worked with this sort of stuff quite a bit, I can assure you that OSM is pretty terrible for Geocoding and reverse geocoding. OSM is great for all kinds of roads (everything from the largest highways to the tiniest unofficial hiking trails), pretty good for landuse and absolutely terrible for building footprints and addresses. In many countries you don't have to get far outside of major cities before half the buildings are just missing, and even the buildings that do exist very often have the wrong address or house number.